When General Hummel turns renegade, captures Alcatraz, and threatens to set off a biological weapon that will affect most of San Francisco, the joint FBI and military forces call in a biological weapons expert, Stanley Godspeed. Only one person - still living - had ever escaped from Alcatraz. A British espionage agent who has been held without trial for a long time because he refuses to hand over information that coudl cause national embarrassment - John Patrick Mason.
Plans are drawn up for a small SEAL task force to penetrate Alcatraz. The SEAL team leader is Commander Charles Anderson. Mason finds a way to get the SEAL team into Alcatraz but their presence is detected. In the ensuing firefight, the SEAL team is slaughtered in the shower room to the last man. Mason and Godspeed must now work alone to find the biological weapon and disarm it before the military bomb Alcatraz.