Mog gets into trouble with the Thomas family because she forgets all kinds of things. Mr Thomas says, "Bother that cat!" when Mog forgets her cat flap and sits in his window box meowing to be let in. Mrs Thomas says, "Bother that cat!" when Mog goes to sleep on her best hat. Even Debbie gets annoyed sometimes.
But one night when Mog thinks nobody likes her, she sees a man in the family kitchen and tries to make a friend . . . Suddenly everyone is very pleased with Mog - except the burglar!