When police inspector Gerald Blake wants to infiltrate a London stolen-goods gang, he does a thorough job of it. First, he robs a jewelry store, gets caught and is sentenced to prison. Then he teams up with gang-member Joey to make their escape. Once in the gang, Blake identifies the boss, Larry, and most of the other thieves, but not the "inside man." As a big fur job looms closer, the detective's task is complicated by the playful but seductive advances of Judy, a dazzling blonde who happens also to be the jealous Larry's girl friend.