After an important nuclear scientist is murdered in the hospital while recovering from radiation burns, National Bureau of Investigation agent Duff is called in to investigate. With the help of the scientist's assistant, Cristal, Duff's trail leads him to an international communist
conspiracy. Persoff and Jeffreys are two scientists who want to start WW III by exploding a homemade nuclear bomb in Los Angeles. Duff corners Persoff at the local communist headquarters where the bomb already has been triggered and is exposed to a deadly dose of radiation. Having nothing left to
lose, he flies the bomb over the middle of the ocean, sacrificing himself to save the city. ...