"Big Tim" Halloran retires as Police Chief, and hopes his son, Tim, will join the police force. But the son opts for racketeering and, running a garage for Velvikak Taxicabs. He uses his father's police entrée for knowledge of squad car activity, leads a gang on bold holdup jobs in the heart of the city. Tim's boyhood friend, Allen Coltrin, works in the police lab. Myrna Kingsley, daughter of the new chief, wavers between Tim and Allen with her affection. All are on a collision course that does not bode well for two of them.