When General Hummel and his renegade squad of US Marines take over the former Alcatraz prison, the safety of San Francisco hangs in the balance. Then they threaten to launch a poison gas attack on the city if no-one meets their demands. So the FBI’s response is to call in Stanley Goodspeed, a nerdy weapons expert, and John Patrick Mason, a former SAS man and send them together into the prison complex. Can this unlikely pairing prevent mass murder? The free world holds its breath.