When Wallace rents out Gromit’s old bedroom to a quiet penguin lodger, Gromit quickly finds himself pushed aside and suspicious of the newcomer. The penguin soon shows a troubling interest in Wallace’s ex-NASA Techno Trousers, which have been modified to take Gromit on walks. As Gromit investigates, he discovers the lodger is no ordinary tenant, but a wanted criminal with a sinister plan.