 Rogers Henry, former head of the Defense Department s Medusa Project at Los Alamos, cons his estranged wife Vivian into transporting a "prototype" bomb to the Pentagon. Vivian accompanies the "prototype" bomb onto a Boeing 737 cargo flight, and once the jet is in the air, the count-down sequence is accidentally initiated. The crew discovers it is no prototype, but a working Medusa weapon capable of sending out an electro-magnetic pulse that would disrupt electronic communication across the continent. They also learn Rogers has synchronized the detonator with the frequency of Vivian s pacemaker, so that if she walks out of range the bomb will immediately go off.