Molly and Jake are brother and sister mice looking for a new place to live when they discover Public School 42. Molly manages to squeeze through a crack in the foundation while Jake, too plump to make it through, gets stuck on the playground with a nasty cat called Big Gray. While Jake fights for his life, Molly meets Miss Clark's class pets. Gino, a gentle and kind hamster, is mysterious to say the least. he introduces Molly to Peaches, a plump white abbit who used to belong to a magician, and a wacky pair of lovebirds named Prince and Princess. While Jake battles an owl, and barely excapes death by fire, Molly thinks she's found her dream home. Maybe one day she might even do the impossible and become a class pet herself. But she hasn't yet tangled with the bully Big Gray. And how will Jake react when he finds out that P.S. 42 is haunted?