A young convict, Chuck Spillers, strikes up a friendship with Martin Brueck, an elderly prison visitor who owns a pet shop. When Chuck is released, he is glad to take a job working in the shop. The old man confides that he was in a Nazi concentration camp, during the war. Chuck finds that Martin keeps a number of large cats in cages and is experimenting in controlling animals by electrical force fields and bells. When he opens Martin's safe, he learns that Martin was not exactly a concentration camp inmate. Chuck is again held captive, this time by a mad former Nazi who will stop at nothing - and when his wife, Annie, comes looking for him, she is captured, too. At the end, they seem to have turned the tables on Martin and escaped from his clutches - but have they?