Sycorax and Caliban are Mrs. Baker's pet rats, given to her by Lieutenant Baker back when the rats were babies and still cute. In the present, they're huge, scabby, and have yellow teeth. Holling thinks they look possessed, and everyone is terrified to go near them. The rats escape in October and spend much of the school year living in the walls and the ceiling of Mrs. Baker's classroom. After several months, the exterminator is called to get rid of the rats, but even he is afraid of them. Finally, after chasing Holling across the tennis courts, the rats are hit by a bus.