During a routine flight to Minneapolis–Saint Paul, a passenger (Susan Dey) aboard Global Airways Flight 502, a Boeing 707, discovers a bomb threat written on the mirror of one of the first-class bathrooms. A second threat is soon found left on a napkin in a galley. Captain Hank O'Hara (Charlton Heston) takes the cryptic threats seriously and follows the instructions -- "Bomb on plane divert to Anchorage Alaska. No Joke, No Tricks. Death"—by changing course for Alaska. To avoid an explosive decompression if a bomb goes off, he flies at lower altitude, increasing fuel consumption.