After private detective Mike Hammer (Robert Bray) defends a prostitute (Jan Chaney) from a violent thug, she's killed in what looks like a hit-and-run accident. But her ring -- once stolen by Nazis -- is again missing. After Capt. Pat Chambers (Booth Coleman) briefs Mike, he embarks on a search to find the ring and unravel the mystery surrounding the murder. Along the way, he meets a beautiful widow, Nancy (Whitney Blake), and must confront a gang of jewel smugglers.