Chicago is paralyzed by a snowstorm affecting Lincoln International Airport. A Trans Global Airlines (TGA) Boeing 707 flight crew misjudge their turn from Runway 29 onto the taxiway, becoming stuck in the snow and closing Runway 29. Airport manager Mel Bakersfeld (Burt Lancaster) is forced to work overtime, causing tension with his wife, Cindy (Dana Wynter). Divorce is looming as he nurtures a closer relationship with a co-worker, TGA customer relations agent Tanya Livingston (Jean Seberg).
Vernon Demarest (Dean Martin) is a TGA captain scheduled to be the checkride captain for TGA to evaluate Captain Anson Harris (Barry Nelson) during TGA's Flight 2 to Rome. Flight 2, TGA's flagship service, is being operated by a Boeing 707 named The Golden Argosy. Although Demarest is married to Bakersfeld's sister, Sarah (Barbara Hale), he is secretly having an affair with Gwen Meighen (Jacqueline Bisset), chief stewardess on the flight, who informs him before takeoff that she is pregnant with his child.
Bakersfeld borrows TWA mechanic Joe Patroni (George Kennedy) to assist with TGA's disabled plane. Meanwhile Bakersfeld and Livingston also deal with Mrs. Ada Quonsett (Helen Hayes), an elderly lady who is a habitual stowaway.
Demolition expert D.O. Guerrero (Van Heflin), down on his luck and with a history of mental illness, buys life insurance with the intent of committing suicide by blowing up The Golden Argosy. He plans to set off a bomb in an attachÃ© case while over the Atlantic so that his wife, Inez (Maureen Stapleton), will collect the insurance money of $225,000. His erratic behavior at the airport, including using his last cash to buy the insurance policy and mistaking a Customs officer for an airline ramp agent, attracts airport officials' attention. Meanwhile Guerrero's wife finds a Special Delivery envelope from a travel agency and, realizing her husband might be doing something desperate, goes to the airport to try to him. She informs airport officials that he had been fired from a construction job for "misplacing" explosives and that the family's financial situation was desperate.
Mrs. Quonsett slips away from Bakersfeld and Livingston, slips past the gate agent (passenger security screening did not yet exist), boards Flight 2, and happens to sit next to Guerrero. When the Golden Argosy crew is made aware of Guerrero's presence and possible intentions, they turn the plane back toward Chicago without informing the passengers. Once Quonsett is discovered, her help is enlisted by the crew to get to Guerrero's briefcase, but the ploy fails when a would-be helpful male passenger unwittingly returns the case to Guerrero.
Captain Demarest then goes back into the passenger cabin and tries to persuade Guerrero not to trigger the bomb, informing him that his insurance policy will be useless. Guerrero briefly considers giving Demarest the bomb, but just then another passenger exits the lavatory at the rear of the aircraft, and the same would-be helpful passenger yells out that he should jump Guerrero, who has a bomb. Guerrero runs into the lavatory, locks it, and sets off the device. The detonation blows out a hole in the wall of the lavatory and Guerrero with it. Gwen, just outside the door, is injured in the explosion and subsequent explosive decompression, but the pilots retain control of the airplane.
With all airports east of Chicago unusable due to bad weather, they return to Lincoln International for an emergency landing. Due to the bomb damage, Captain Demarest demands the airport's longest runwayâRunway 29, which is still closed due to the stuck airliner. Eventually Bakersfeld orders the plane to be pushed off the runway by snowplows, despite the costly damage they would do to it. Patroni, who is "taxi-qualified" on Boeing 707s, has been trying to move the stuck aircraft in time for Demarest's damaged aircraft to land. By exceeding the Boeing 707's engine operating parameters, Patroni frees the stuck jet without damage, allowing Runway 29 to be reopened just in time for the crippled Golden Argosy to land.
In a brief epilogue, Ada Quonsett is enjoying her reward of free first-class travel on TGA. But as she arrives at the gate, she laments that it was "much more fun the other way."
Where did Guerrero go to detonate the bomb?
Lavatory