diff --git a/concepts/higher-order-functions/.meta/config.json b/concepts/higher-order-functions/.meta/config.json
new file mode 100644
index 00000000..4070de02
--- /dev/null
+++ b/concepts/higher-order-functions/.meta/config.json
@@ -0,0 +1,7 @@
+{
+  "authors": [
+    "kahgoh"
+  ],
+  "contributors": [],
+  "blurb": "Functions are first class citizens in Kotlin and can be assigned to variables or passed to other functions."
+}
diff --git a/concepts/higher-order-functions/about.md b/concepts/higher-order-functions/about.md
new file mode 100644
index 00000000..ceaa58a1
--- /dev/null
+++ b/concepts/higher-order-functions/about.md
@@ -0,0 +1,101 @@
+# About Higher Order Functions
+
+Functions in Kotlin are first class citizens.
+This means they can be stored in variables, passed as arguments and even returned by other functions.
+For example, assigning a function to the variable `addOne`:
+
+```kotlin
+val addOne = fun (num : Int) : Int {
+    return num + 1
+}
+```
+
+A function can also return another function:
+
+```kotlin
+fun makeAddOne() : (Int) -> Int {
+    return fun(num : Int) : Int {
+        return num + 1
+    }
+}
+```
+
+Once assigned, the function can be called through the variable as if it was just another function:
+```kotlin
+addOne(3)
+// => 4
+```
+
+## Declaring function types
+
+A variable or parameter type can be declared using the syntax `(parameter types) -> return type`.
+For example, declaring a variable:
+
+```kotlin
+val addOne : (Int) -> Int = fun (num : Int) : Int {
+    return num + 1
+}
+```
+
+And for a function parameter:
+
+```kotlin
+fun perform(operation : (Int) -> Int) {
+    operation(3)
+}
+```
+
+## Lambda expressions
+
+A lambda expression is a shorter way of defining a function.
+They are written in the form `{ parameters -> body }`.
+The expression returns the last value from the last statement in the body.
+For example:
+
+```kotlin
+// Assigning to a variable
+val addOne = { num : Int -> num +  1}
+
+// In a function call
+perform({ num : Int -> num + 1 })
+```
+
+Kotlin can infer types when there is enough information.
+For example, the above examples can also be written as:
+
+```kotlin
+// Assigning to a variable
+val addOne : (Int) -> Int = { num -> num + 1 }
+
+// Or ...
+val addOne  = { num : Int -> num + 1 }
+
+// Using in a function
+perform({ num -> num + 1 })
+```
+
+## `it` for single parameter lambdas
+
+When the expression has just one parameter, the parameter can be omitted.
+Kotlin will then make a parameter called `it` available in the body.
+For example:
+
+```kotlin
+val addOne : (Int) -> Int = { it +  1 }
+```
+
+## Passing trailing lambdas
+
+When the last argument to a function is a lambda, the lambda expression is written directly _after_ the parentheses.
+For example:
+
+```kotlin
+// Function that takes a function as last argument
+fun calculateFrom(from : Int, operation : (Int) -> Int) : Int {
+    return operation(from)
+}
+
+// Call the calculateFrom function
+calculateFrom(2) { it * 3 }
+// => 6
+```
diff --git a/concepts/higher-order-functions/introduction.md b/concepts/higher-order-functions/introduction.md
new file mode 100644
index 00000000..ceaa58a1
--- /dev/null
+++ b/concepts/higher-order-functions/introduction.md
@@ -0,0 +1,101 @@
+# About Higher Order Functions
+
+Functions in Kotlin are first class citizens.
+This means they can be stored in variables, passed as arguments and even returned by other functions.
+For example, assigning a function to the variable `addOne`:
+
+```kotlin
+val addOne = fun (num : Int) : Int {
+    return num + 1
+}
+```
+
+A function can also return another function:
+
+```kotlin
+fun makeAddOne() : (Int) -> Int {
+    return fun(num : Int) : Int {
+        return num + 1
+    }
+}
+```
+
+Once assigned, the function can be called through the variable as if it was just another function:
+```kotlin
+addOne(3)
+// => 4
+```
+
+## Declaring function types
+
+A variable or parameter type can be declared using the syntax `(parameter types) -> return type`.
+For example, declaring a variable:
+
+```kotlin
+val addOne : (Int) -> Int = fun (num : Int) : Int {
+    return num + 1
+}
+```
+
+And for a function parameter:
+
+```kotlin
+fun perform(operation : (Int) -> Int) {
+    operation(3)
+}
+```
+
+## Lambda expressions
+
+A lambda expression is a shorter way of defining a function.
+They are written in the form `{ parameters -> body }`.
+The expression returns the last value from the last statement in the body.
+For example:
+
+```kotlin
+// Assigning to a variable
+val addOne = { num : Int -> num +  1}
+
+// In a function call
+perform({ num : Int -> num + 1 })
+```
+
+Kotlin can infer types when there is enough information.
+For example, the above examples can also be written as:
+
+```kotlin
+// Assigning to a variable
+val addOne : (Int) -> Int = { num -> num + 1 }
+
+// Or ...
+val addOne  = { num : Int -> num + 1 }
+
+// Using in a function
+perform({ num -> num + 1 })
+```
+
+## `it` for single parameter lambdas
+
+When the expression has just one parameter, the parameter can be omitted.
+Kotlin will then make a parameter called `it` available in the body.
+For example:
+
+```kotlin
+val addOne : (Int) -> Int = { it +  1 }
+```
+
+## Passing trailing lambdas
+
+When the last argument to a function is a lambda, the lambda expression is written directly _after_ the parentheses.
+For example:
+
+```kotlin
+// Function that takes a function as last argument
+fun calculateFrom(from : Int, operation : (Int) -> Int) : Int {
+    return operation(from)
+}
+
+// Call the calculateFrom function
+calculateFrom(2) { it * 3 }
+// => 6
+```
diff --git a/concepts/higher-order-functions/links.json b/concepts/higher-order-functions/links.json
new file mode 100644
index 00000000..71cf9cc0
--- /dev/null
+++ b/concepts/higher-order-functions/links.json
@@ -0,0 +1,10 @@
+[
+  {
+    "url": "https://kotlinlang.org/docs/functions.html",
+    "description": "Kotlin Functions documentation"
+  },
+  {
+    "url": "https://kotlinlang.org/docs/lambdas.html",
+    "description": "Kotlin Lambdas documentation"
+  }
+]
diff --git a/config.json b/config.json
index 0f44a742..b16671ef 100644
--- a/config.json
+++ b/config.json
@@ -55,6 +55,19 @@
           "basics"
         ],
         "status": "wip"
+      },
+      {
+        "slug": "secret-agent",
+        "name": "secret-agent",
+        "uuid": "96553db0-5b98-4dcd-8a1c-882e42c3751a",
+        "concepts": [
+          "higher-order-functions"
+        ],
+        "prerequisites": [
+          "numbers",
+          "strings"
+        ],
+        "status": "wip"
       }
     ],
     "practice": [
@@ -1196,6 +1209,7 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 6,
+        "status": "deprecated",
         "topics": [
           "conditionals",
           "games",
@@ -1203,8 +1217,7 @@
           "lists",
           "matrices",
           "strings"
-        ],
-        "status": "deprecated"
+        ]
       },
       {
         "slug": "rail-fence-cipher",
diff --git a/exercises/concept/secret-agent/.docs/instructions.md b/exercises/concept/secret-agent/.docs/instructions.md
new file mode 100644
index 00000000..1fc683ff
--- /dev/null
+++ b/exercises/concept/secret-agent/.docs/instructions.md
@@ -0,0 +1,64 @@
+# Instructions
+
+Hello, Agent Double-Null0111.
+
+Your mission, should you choose to accept it, is to write a pair of tools to help you infiltrate UMBRA (United Minions Being Really Awful) headquarters and retrieve the plans for their latest really awful scheme. 
+There are three tools you will need to carry out this mission.
+
+## 1. Generate an id number
+
+Each minion has a unique identifier that changes each day and depends on the number of secrets they hold and the number of hours they sleep.
+You will need to write a function that takes the day (as an `Int`) and creates an identifier generating function for the day.
+The identifier is calculated by:
+
+1. Multiply the number of secrets held by the number of hours they sleep
+2. Add the day (represented as an `Int`) to the result
+
+```kotlin
+val idGenerator = makeIdGenerator(4)
+idGenerator(3, 6)
+// => 22
+
+idGenerator(11, 5)
+//  => 59
+```
+
+## 2. Protect the recovered secret plans with a secret password
+
+Once you have the secret plans, you will need to protect it so that only those who know the password can recover them.
+In order to do this, you will need to implement the function `protectSecret(secret: String, password: String) : (String) -> String`.
+This function will return another function that takes possible password strings as input.
+If the entered password is correct the new function returns the hidden secret, but if the password is incorrect, the function returns "Sorry. No hidden secrets here."
+
+```kotlin
+val secretFunction = protectSecret("Steal the world's supply of french fries!", "5up3r53cr37")
+
+secretFunction("Open sesame")
+// Returns "Sorry. No hidden secrets here."
+
+secretFunction("5up3r53cr37")
+// Returns "Steal the world's supply of french fries!"
+```
+
+## 3. Find the secret password
+
+The UMBRA base has a number of rooms guarded by a security guard who will ask you for the secret password.
+The secret password depends on the room'sS number.
+Unfortunately, we have know only half of the algorithm for working out the password.
+The other half can be found by asking one of the minions.
+
+Implement the `getPassword` function that takes in the room number and the minion's function and returns the secret password.
+The secret number is obtained by calling the minion's function with another function representing the algorithm known by us.
+Our part of the algorithm:
+
+1. Takes two numbers and adds them together
+2. Multiplies the result by the room id
+
+```kotlin
+val minionFunction = { yourFunc : (Int, Int) -> Int ->
+    "Password=${yourFunc(1, 3)}"
+}
+
+getPassword(5, minionFunction)
+// Returns "Password=20"
+```
diff --git a/exercises/concept/secret-agent/.docs/introduction.md b/exercises/concept/secret-agent/.docs/introduction.md
new file mode 100644
index 00000000..f37f43a1
--- /dev/null
+++ b/exercises/concept/secret-agent/.docs/introduction.md
@@ -0,0 +1,101 @@
+# Introduction
+
+Functions in Kotlin are first class citizens.
+This means they can be stored in variables, passed as arguments and even returned by other functions.
+For example, assigning a function to the variable `addOne`:
+
+```kotlin
+val addOne = fun (num : Int) : Int {
+    return num + 1
+}
+```
+
+A function can also return another function:
+
+```kotlin
+fun makeAddOne() : (Int) -> Int {
+    return fun(num : Int) : Int {
+        return num + 1
+    }
+}
+```
+
+Once assigned, the function can be called through the variable as if it was just another function:
+```kotlin
+addOne(3)
+// => 4
+```
+
+## Declaring function types
+
+A variable or parameter type can be declared using the syntax `(parameter types) -> return type`.
+For example, declaring a variable:
+
+```kotlin
+val addOne : (Int) -> Int = fun (num : Int) : Int {
+    return num + 1
+}
+```
+
+And for a function parameter:
+
+```kotlin
+fun perform(operation : (Int) -> Int) {
+    operation(3)
+}
+```
+
+## Lambda expressions
+
+A lambda expression is a shorter way of defining a function.
+They are written in the form `{ parameters -> body }`.
+The expression returns the last value from the last statement in the body.
+For example:
+
+```kotlin
+// Assigning to a variable
+val addOne = { num : Int -> num +  1}
+
+// In a function call
+perform({ num : Int -> num + 1 })
+```
+
+Kotlin can infer types when there is enough information.
+For example, the above examples can also be written as:
+
+```kotlin
+// Assigning to a variable
+val addOne : (Int) -> Int = { num -> num + 1 }
+
+// Or ...
+val addOne  = { num : Int -> num + 1 }
+
+// Using in a function
+perform({ num -> num + 1 })
+```
+
+## `it` for single parameter lambdas
+
+When the expression has just one parameter, the parameter can be omitted.
+Kotlin will then make a parameter called `it` available in the body.
+For example:
+
+```kotlin
+val addOne : (Int) -> Int = { it +  1 }
+```
+
+## Passing trailing lambdas
+
+When the last argument to a function is a lambda, the lambda expression is written directly _after_ the parentheses.
+For example:
+
+```kotlin
+// Function that takes a function as last argument
+fun calculateFrom(from : Int, operation : (Int) -> Int) : Int {
+    return operation(from)
+}
+
+// Call the calculateFrom function
+calculateFrom(2) { it * 3 }
+// => 6
+```
diff --git a/exercises/concept/secret-agent/.meta/config.json b/exercises/concept/secret-agent/.meta/config.json
new file mode 100644
index 00000000..02e13ac5
--- /dev/null
+++ b/exercises/concept/secret-agent/.meta/config.json
@@ -0,0 +1,20 @@
+{
+  "authors": [
+    "kahgoh"
+  ],
+  "files": {
+    "solution": [
+      "src/main/kotlin/SecretAgent.kt"
+    ],
+    "test": [
+      "src/test/kotlin/SecretAgentTest.kt"
+    ],
+    "exemplar": [
+      ".meta/src/reference/kotlin/SecretAgent.kt"
+    ]
+  },
+  "forked_from": [
+    "swift/secret-agent"
+  ],
+  "blurb": "Learn about higher-order functions by becoming a spy and infiltrate the secret UMBRA headquarters"
+}
diff --git a/exercises/concept/secret-agent/.meta/design.md b/exercises/concept/secret-agent/.meta/design.md
new file mode 100644
index 00000000..0b559d97
--- /dev/null
+++ b/exercises/concept/secret-agent/.meta/design.md
@@ -0,0 +1,21 @@
+# Design
+
+## Goal
+
+The goal of this exercise is to teach students about higher order functions and lambda expressions in Kotlin.
+
+## Learning objectives
+
+- How to write lambda expressions
+- How to pass a function to another function
+- How to call a function from a variable or function parameter
+
+## Out of scope
+
+## Concepts
+
+- `higher-order-functions`: Know about lambda expressions in Kotlin and how to assign them to variables; how to pass them to other functions; how to return them; how to invoke them 
+
+## Prerequisites
+
+Strings and numbers are used in the exercise.
\ No newline at end of file
diff --git a/exercises/concept/secret-agent/.meta/src/reference/kotlin/SecretAgent.kt b/exercises/concept/secret-agent/.meta/src/reference/kotlin/SecretAgent.kt
new file mode 100644
index 00000000..e684638c
--- /dev/null
+++ b/exercises/concept/secret-agent/.meta/src/reference/kotlin/SecretAgent.kt
@@ -0,0 +1,17 @@
+fun makeIdGenerator(day : Int) : (Int, Int) -> Int {
+    return {num1 : Int, num2 : Int -> num1 * num2 + day}
+}
+
+fun protectSecret(secret : String, password : String) : (String) -> String {
+    return {
+        if (it == password) {
+            secret
+        } else {
+            "Sorry. No hidden secrets here."
+        }
+    }
+}
+
+fun getPassword(room : Int, minionFunction : ((Int, Int) -> Int) -> String) : String {
+    return minionFunction {num1 : Int, num2 : Int -> (num1 + num2) * room}
+}
diff --git a/exercises/concept/secret-agent/build.gradle.kts b/exercises/concept/secret-agent/build.gradle.kts
new file mode 100644
index 00000000..3db5dc4f
--- /dev/null
+++ b/exercises/concept/secret-agent/build.gradle.kts
@@ -0,0 +1,23 @@
+import org.gradle.api.tasks.testing.logging.TestExceptionFormat
+
+plugins {
+    kotlin("jvm")
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation(kotlin("stdlib-jdk8"))
+    
+    testImplementation("junit:junit:4.13.2")
+    testImplementation(kotlin("test-junit"))
+}
+
+tasks.withType<Test> {
+    testLogging {
+        exceptionFormat = TestExceptionFormat.FULL
+        events("passed", "failed", "skipped")
+    }
+}
diff --git a/exercises/concept/secret-agent/gradle/wrapper/gradle-wrapper.jar b/exercises/concept/secret-agent/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 00000000..7f93135c
Binary files /dev/null and b/exercises/concept/secret-agent/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/exercises/concept/secret-agent/gradle/wrapper/gradle-wrapper.properties b/exercises/concept/secret-agent/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 00000000..3fa8f862
--- /dev/null
+++ b/exercises/concept/secret-agent/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/exercises/concept/secret-agent/gradlew b/exercises/concept/secret-agent/gradlew
new file mode 100755
index 00000000..1aa94a42
--- /dev/null
+++ b/exercises/concept/secret-agent/gradlew
@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/exercises/concept/secret-agent/gradlew.bat b/exercises/concept/secret-agent/gradlew.bat
new file mode 100644
index 00000000..93e3f59f
--- /dev/null
+++ b/exercises/concept/secret-agent/gradlew.bat
@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/exercises/concept/secret-agent/settings.gradle.kts b/exercises/concept/secret-agent/settings.gradle.kts
new file mode 100644
index 00000000..054e2f7e
--- /dev/null
+++ b/exercises/concept/secret-agent/settings.gradle.kts
@@ -0,0 +1,13 @@
+pluginManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+    }
+    resolutionStrategy {
+        eachPlugin {
+            when (requested.id.id) {
+                "org.jetbrains.kotlin.jvm" -> useModule("org.jetbrains.kotlin:kotlin-gradle-plugin:1.6.0")
+            }
+        }
+    }
+}
diff --git a/exercises/concept/secret-agent/src/main/kotlin/SecretAgent.kt b/exercises/concept/secret-agent/src/main/kotlin/SecretAgent.kt
new file mode 100644
index 00000000..6f03c1fa
--- /dev/null
+++ b/exercises/concept/secret-agent/src/main/kotlin/SecretAgent.kt
@@ -0,0 +1,11 @@
+fun makeIdGenerator(day : Int) : (Int, Int) -> Int {
+    TODO("Please implement the makeIdGenerator() function")
+}
+
+fun protectSecret(secret : String, password : String) : (String) -> String {
+    TODO("Please implement the protectSecret() function")
+}
+
+fun getPassword(room : Int, minionFunction : ((Int, Int) -> Int) -> String) : String {
+    TODO("Please implement the getPassword() function")
+}
diff --git a/exercises/concept/secret-agent/src/test/kotlin/SecretAgentTest.kt b/exercises/concept/secret-agent/src/test/kotlin/SecretAgentTest.kt
new file mode 100644
index 00000000..68875fe5
--- /dev/null
+++ b/exercises/concept/secret-agent/src/test/kotlin/SecretAgentTest.kt
@@ -0,0 +1,56 @@
+import org.junit.Assert.assertEquals
+import kotlin.test.Test
+
+class SecretAgentTest() {
+    val protectedSecret = protectSecret("UMBRA will fill everyone's sugar bowls with salt!", "P455w0rd")
+
+    val minionFunction1 = { yourFunc : (Int, Int) -> Int ->
+        "Password=${yourFunc(1, 3)}"
+    }
+
+    val minionFunction2 = { yourFunc : (Int, Int) -> Int ->
+        "UMBRA's favourite number is ${yourFunc(7, 11)}"
+    }
+
+    @Test
+    fun `id generator make id for day 1`() {
+        val idGenerator = makeIdGenerator(1)
+        assertEquals(29, idGenerator(4, 7))
+    }
+
+    @Test
+    fun `id generator make id for day 4`() {
+        val idGenerator = makeIdGenerator(4)
+        assertEquals(22, idGenerator(3, 6))
+    }
+
+    @Test
+    fun `protected secret returns secret with correct password`() {
+        assertEquals("UMBRA will fill everyone's sugar bowls with salt!", protectedSecret("P455w0rd"))
+    }
+
+    @Test
+    fun `protected secret returns fail message with incorrect password`() {
+        assertEquals("Sorry. No hidden secrets here.", protectedSecret("password"))
+    }
+
+    @Test
+    fun `get password for room 5`() {
+        assertEquals("Password=20", getPassword(5, minionFunction1))
+    }
+
+    @Test
+    fun `get password for room 17`() {
+        assertEquals("Password=68", getPassword(17, minionFunction1))
+    }
+
+    @Test
+    fun `get password for room 5 with second function`() {
+        assertEquals("UMBRA's favourite number is 90", getPassword(5, minionFunction2))
+    }
+
+    @Test
+    fun `get password for room 17 with second function`() {
+        assertEquals("UMBRA's favourite number is 306", getPassword(17, minionFunction2))
+    }
+}
\ No newline at end of file
diff --git a/exercises/settings.gradle.kts b/exercises/settings.gradle.kts
index bc770812..f001d236 100644
--- a/exercises/settings.gradle.kts
+++ b/exercises/settings.gradle.kts
@@ -1,4 +1,5 @@
 include(
+    "concept:secret-agent",
     "practice:accumulate",
     "practice:acronym",
     "practice:all-your-base",