Circleen goes to Turkey on holiday with her artist. Her chums Ingolf, Fredrik, and Viktor decide go to see her, and they stow away on board granddad’s ship, which is also heading south. On board they meet another stowaway, a tough, fearless mouse by the name of Ali, who has set off into the world in search of happiness. Granddad is furious: he doesn’t want kids on board, and the cat, the cook, and the captain aren’t exactly mouse lovers either. Meanwhile, Ali has a secret!