Tough L.A. private eye Mike Hammer gives a ride to Christina, a frightened young woman he finds running along the road one night. His car is run off the road by unseen thugs. Hammer is knocked out and Christina is tortured in an unsuccessful attempt to get information from her. They are put back into Hammer's car which then is forced off a cliff. Hammer wakes up in the hospital. Velda, his trusty secretary, informs him that Christina is dead. Pat Chambers, Mike's policeman friend, tells him to stay off the case, but Mike thinks it might be a big story--meaning big money for him--because the FBI is interested. He, Velda, and Nick, his garage mechanic friend, start investigating in hopes of finding out why Christina was killed.