When U.S. Customs agent Cliff Holden learns his childhood best friend has been murdered, he sets out to find the killer. His friend, who was also an agent, had been on the trail of some jewel thieves before his death, so Holden picks up the investigation. He travels to Europe then catches a return flight back to New York - on the same plane as the suspect. Holden's flight also leads him to a Dutch beauty who happens to be wearing a stolen jewel, and who turns to him for help before falling ill on the plane. Can Holden solve the mystery? "C"-Man is a classic film noir thriller.