When vengeful General Francis X. Hummel seizes control of Alcatraz Island and threatens to launch missiles loaded with deadly chemical weapons into San Francisco, only a young FBI chemical weapons expert and notorious Federal prisoner have the stills to penetrate the impregnable island fortress and take him down. A mild-mannered chemist and an ex-con must lead the counterstrike when a rogue group of military men, led by a renegade general, threaten a nerve gas attack from Alcatraz against San Francisco.