Mark Sheldon (Robert Wilcox) is an undercover secret service operative. He is assigned to investigate a modern time slave organization on a desert island way out in the Pacific. The organization hires prison convicts on parole and puts them into hard labor on the island, where they are unable to leave when they wish. Sheldon’s partner on the case is just about to reveal that the head of the racketeering operation on the island is a man named Stephen Danel (Peter Lorre), when he gets murdered. Sheldon suspects that Danel has ordered the kill and decides to go on investigating on his own.