A man is killed in an apparently random attack, and suspicion falls on a gang of muggers. Only Detective Sergeant Geraldine Steel thinks this is the work of a more deliberate murderer. Two more victims are discovered, after further seemingly indiscriminate attacks. The muggers are tracked down, with tragic consequences. And all the while the killer remains at large. When Geraldine finally manages to track down a witness, she finds her own life is in danger.