San Francisco International Airport

Airport manager Jim Conrad learns that a military shipment of deadly gas is set to detonate due to a frustrated anti-war scientist, Professor Theodore Tragis. Tragis plans to go on national television to explain his actions, which he claims represent "peace through destruction." Having previously worked in the chemical warfare program, Tragis sabotages a gas tank at San Francisco Airport and leaves a message about the impending disaster. A colonel warns Conrad that gas masks won't help against this threat. As Tragis broadcast his anti-war sentiments, Conrad and his chief of security, Hatten, quickly assessed the situation. With the help of Branch, a naval commander and poison gas expert, Conrad orders a complete evacuation of the airport, leaving it eerily empty.