The safety of San Francisco hangs in the balance when General Francis X. Hummel (Ed Harris) and his renegade squad of US Marines take over the abandoned Alcatraz prison and threaten to launch a poison gas attack on the city if their demands are not met. The FBI's response is to call in Stanley Goodspeed (Nicolas Cage), a nerdy weapons expert, and John Patrick Mason (Sean Connery), a former SAS man who has been in prison for the last 30 years, and send them together into the prison complex.

Can this unlikely pairing prevent mass murder? The free world holds its breath.