Mike is hired to retrieve incriminating letters from a blackmailer, but soon learns that the package with $50,000 was really the ransom money to payoff kidnappers. When the woman who collected the ransom from Hammer is double-crossed, she tries to get revenge on her partner but is killed before she can meet with the private detective. Hammer investigates the dead woman's friends and co-workers to mete out his kind of justice upon the kidnapping murderer.