diff --git a/apps/api/src/turn-in/turn-in.service.spec.ts b/apps/api/src/turn-in/turn-in.service.spec.ts
index 698f7d0..8bf9405 100644
--- a/apps/api/src/turn-in/turn-in.service.spec.ts
+++ b/apps/api/src/turn-in/turn-in.service.spec.ts
@@ -1,3 +1,4 @@
+import { HttpException } from '@nestjs/common';
 import { DataSource, EntityManager, EntityTarget } from 'typeorm';
 import { Character } from '../characters/entities/character.entity';
 import { CharacterItem } from '../items/entities/character-item.entity';
@@ -168,6 +169,30 @@ async function expectTurnInDomainError(promise: Promise<unknown>, code: string):
   expect(error.code).toBe(code);
 }
 
+/**
+ * `characterNotFound` is shared from `travel.errors`, so it is not a
+ * TurnInDomainError. Assert on the wire contract -- code plus status --
+ * the way `reputation.service.spec.ts` does for the same shared error.
+ */
+async function expectHttpErrorWithCode(
+  promise: Promise<unknown>,
+  code: string,
+  status: number,
+): Promise<void> {
+  let error: unknown;
+  try {
+    await promise;
+  } catch (cause) {
+    error = cause;
+  }
+  expect(error).toBeInstanceOf(HttpException);
+  if (!(error instanceof HttpException)) {
+    throw new Error('Expected HttpException');
+  }
+  expect(error.getStatus()).toBe(status);
+  expect(error.getResponse()).toMatchObject({ code });
+}
+
 describe('TurnInService', () => {
   describe('turnIn', () => {
     it('consumes the exact quantity, grants silver and reputation atomically', async () => {
@@ -232,6 +257,19 @@ describe('TurnInService', () => {
       expect(state.characters[0].silver).toBe(10);
     });
 
+    it('rejects an unknown character, mutating nothing', async () => {
+      const { service, state } = createService(createState());
+
+      await expectHttpErrorWithCode(
+        service.turnIn('unknown-character', 'ash-pelt-border-guard', 1),
+        'CHARACTER_NOT_FOUND',
+        404,
+      );
+      expect(state.characterItems[0].quantity).toBe(5);
+      expect(state.characters[0].silver).toBe(10);
+      expect(state.characterReputation).toHaveLength(0);
+    });
+
     it('rejects a disabled turn-in', async () => {
       const state = createState({ turnIns: [turnInDefinition({ enabled: false })] });
       const { service } = createService(state);