diff --git a/minmax-rs/src/connect4/board.rs b/minmax-rs/src/connect4/board.rs
index 5c7c39f..4a7362b 100644
--- a/minmax-rs/src/connect4/board.rs
+++ b/minmax-rs/src/connect4/board.rs
@@ -27,6 +27,10 @@ impl Connect4 {
         }
     }
 
+    pub fn set_pos(&mut self, position: usize, value: Position) {
+        self.positions[position] = value;
+    }
+
     pub fn result(&self) -> State {
         match self.check_board() {
             State::Winner(winner) => State::Winner(winner),
diff --git a/minmax-rs/src/lib.rs b/minmax-rs/src/lib.rs
index 9dd3cfe..3883424 100644
--- a/minmax-rs/src/lib.rs
+++ b/minmax-rs/src/lib.rs
@@ -92,6 +92,7 @@ impl Score {
         Self(int)
     }
 
+    #[allow(unused)]
     fn randomize(self) -> Self {
         let score = self.0 as f32;
         let rand = rand::thread_rng();
diff --git a/minmax-rs/src/minmax.rs b/minmax-rs/src/minmax.rs
index 07ed8ff..84bcac3 100644
--- a/minmax-rs/src/minmax.rs
+++ b/minmax-rs/src/minmax.rs
@@ -29,6 +29,10 @@ impl<G: Game> PerfectPlayer<G> {
         self
     }
 
+    pub fn best_move(&self) -> G::Move {
+        self.best_move.expect("no move made yet")
+    }
+
     fn minmax(&mut self, board: &mut G, player: Player, depth: usize) -> Score {
         if let Some(max_depth) = self.max_depth && depth >= max_depth {
             return board.rate(player);
diff --git a/rs-wrapper/ch_bbw_m411_connect4_RustPlayer.h b/rs-wrapper/ch_bbw_m411_connect4_RustPlayer.h
index e6348fd..78516b7 100644
--- a/rs-wrapper/ch_bbw_m411_connect4_RustPlayer.h
+++ b/rs-wrapper/ch_bbw_m411_connect4_RustPlayer.h
@@ -10,10 +10,10 @@ extern "C" {
 /*
  * Class:     ch_bbw_m411_connect4_RustPlayer
  * Method:    rustPlay
- * Signature: (B[Lch/bbw/m411/connect4/Connect4ArenaMain/Stone;)I
+ * Signature: (B[B)I
  */
 JNIEXPORT jint JNICALL Java_ch_bbw_m411_connect4_RustPlayer_rustPlay
-  (JNIEnv *, jobject, jbyte, jobjectArray);
+  (JNIEnv *, jclass, jbyte, jbyteArray);
 
 #ifdef __cplusplus
 }
diff --git a/rs-wrapper/src/lib.rs b/rs-wrapper/src/lib.rs
index 149c984..200c458 100644
--- a/rs-wrapper/src/lib.rs
+++ b/rs-wrapper/src/lib.rs
@@ -1,22 +1,81 @@
-// This is the interface to the JVM that we'll call the majority of our
-// methods on.
-use jni::JNIEnv;
-
-// These objects are what you should use as arguments to your native
-// function. They carry extra lifetime information to prevent them escaping
-// this context and getting used after being GC'd.
-use jni::objects::{JClass, JObject};
-
-// This is just a pointer. We'll be returning it from our function. We
-// can't return one of the objects with lifetime information because the
-// lifetime checker won't let us.
+use jni::objects::{JClass, JObject, ReleaseMode};
 use jni::sys::{jbyte, jint};
+use jni::JNIEnv;
 use minmax::{connect4::board::Connect4, GamePlayer};
+use minmax::{PerfectPlayer, Player};
 
-// 0 -> X
-// 1 -> O
-pub fn wrap_player<P: GamePlayer<Connect4>>(current_player: i8, board: ()) -> i32 {
-    0
+/// We need to map the board.
+/// Rust:
+/// ```text
+///  0  1  2  3  4  5  6
+///  7  8  9 10 11 12 13
+/// 14 15 16 17 18 19 20
+/// 21 22 23 24 25 26 27
+/// ```
+/// Java:
+/// ```text
+/// 21 22 23 24 25 26 27
+/// 14 15 16 17 18 19 20
+///  7  8  9 10 11 12 13
+///  0  1  2  3  4  5  6
+/// ```
+fn map_idx(i: usize) -> usize {
+    match () {
+        () if i < 7 => i + 21,
+        () if i < 15 => i + 7,
+        () if i < 21 => i - 7,
+        () => i - 21,
+    }
+}
+
+fn crate_board(java_board: &[i8]) -> Connect4 {
+    let mut board = Connect4::new();
+
+    for i in 0..28 {
+        let java_int = java_board[i];
+        let rust_value = match java_int {
+            0 => Some(Player::X),
+            1 => Some(Player::O),
+            2 => None,
+            _ => unreachable!(),
+        };
+
+        let rust_index = map_idx(i);
+
+        board.set_pos(rust_index, rust_value);
+    }
+
+    board
+}
+
+// 0 -> BLUE -> X
+// 1 -> RED -> O
+// 2 -> empty
+pub fn wrap_player(env: JNIEnv<'_>, current_player: i8, board: JObject<'_>) -> i32 {
+    let board_size = env.get_array_length(board.into_raw()).unwrap();
+    assert_eq!(board_size, 28);
+
+    let byte_array = env
+        .get_byte_array_elements(board.into_raw(), ReleaseMode::NoCopyBack)
+        .unwrap();
+
+    let slice = unsafe { std::slice::from_raw_parts(byte_array.as_ptr() as *const _, 28) };
+
+    let mut board = crate_board(slice);
+
+    let mut player = PerfectPlayer::new(false);
+
+    let current_player_rust = match current_player {
+        0 => Player::X,
+        1 => Player::O,
+        _ => unreachable!(),
+    };
+
+    player.next_move(&mut board, current_player_rust);
+
+    let result_move = player.best_move();
+
+    map_idx(result_move) as i32
 }
 
 // This keeps Rust from "mangling" the name and making it unique for this
@@ -27,9 +86,10 @@ pub extern "system" fn Java_ch_bbw_m411_connect4_RustPlayer_rustPlay(
     // This is the class that owns our static method. It's not going to be used,
     // but still must be present to match the expected signature of a static
     // native method.
-    class: JClass<'_>,
+    _: JClass<'_>,
     player: jbyte,
     board: JObject<'_>,
 ) -> jint {
-    0
+    std::panic::catch_unwind(|| wrap_player(env, player, board))
+        .unwrap_or_else(|_| std::process::abort())
 }