In a whimsical heist in Moominvalley, a group of unlikely heroes must outsmart a cunning thief to save the cherished Moominhouse. What begins as a playful caper soon turns into a dangerous game of cat and mouse, testing the bonds of friendship and loyalty...

When Moominvalley's annual Moonlit Masquerade is disrupted by a mysterious shadow, Moomintroll and his friends must uncover a hidden truth that could change the valley forever....