Former CIA field officer Miles Kendig is intent on publishing an explosive memoir that will also expose the 'dirty tricks' of Myerson, his obnoxious, incompetent, and profane former boss. Myerson and Kendig's protégé Joe Cutter are repeatedly foiled in their attempts to capture the former agent and stop the publication of his memoir. He cleverly stays one step ahead of his pursuers as the chase hopscotches around America and England.
Matthau received a Golden Globe nomination for Best Actor – Motion Picture Musical or Comedy. The Criterion Collection released the film on DVD in 2002.
At Munich's Oktoberfest, Miles Kendig (Matthau) and his CIA team foil a microfilm transfer to an East German spy. Kendig, however, purposely does not apprehend Yaskov, the head of the KGB in Europe. Upon Kendig's return to Washington, his supervisor, Myerson (Beatty), forces him into a desk job because Kendig didn't arrest the Russian. Instead of going in the following Monday as directed, Kendig shreds his personnel file and flies to Salzburg, Austria to visit Isobel Von Schoenenberg (Jackson). Inspired by Yaskov's idea to write his memoirs, Kendig begins a CIA memoir exposing Myerson's dirty tricks and general incompetence. Isobel is horrified, saying that Myerson will send agents to kill him. She nevertheless helps out and mails copies of Kendig's first chapter to spy chiefs in the U.S., Russia, China, France, Italy, and Great Britain. Very quickly, as predicted, Myerson is out to silence Kendig permanently. Yaskov also pursues Kendig for his insider knowledge on all CIA covert operations.
Kendig baits his pursuers by periodically informing them of his location. Leaving Europe, he returns to the U.S., cheerfully renting Myerson's own unoccupied Georgia family home, where he writes a few more chapters. After leaking his address, Kendig induces the FBI to shoot up Myerson's home by saying he has plenty of hoarded firepower. As Kendig sneaks away as part of a pre-planned escape route, the FBI mistake time-delayed firecracker explosions for gunshots and let the bullets and teargas fly, shooting up the home.
Kendig flies to Bermuda by hired seaplane, then on to London to meet with his publisher and present the last chapter of his memoir. Yaskov and CIA agent Cutter (Waterston), a former protégé of Kendig's and friend who has been tasked with pursuing him, exchange information on Kendig. Kendig buys a small biplane and hires an engineer to do custom work on it. Kendig's publisher rebuffs Myerson's threats, and all the pursuers meet up at Kendig's now vacated hotel room. There, they read copies of the book's final chapter left for them.
Kendig later ambushes Cutter in his hotel room, ties him up and gags him, and informs Cutter that he will be flying out in the morning from a small airfield near the English Channel. Isobel gives her CIA minders the slip, crosses the Channel by Hovercraft (Hoverlloyd SR.N4 "Sure") and heads to the airfield. Kendig later reports Cutter's situation to Ross, and everyone converges on the small airfield in the morning. On the way, Kendig suffers a flat tire and is picked up by local police. When a policeman thinks he recognizes him from a fugitive bulletin, Kendig escapes by short-circuiting an electrical socket and stealing their police car.
He reaches the airfield, but the Americans and the Russian are already there via helicopter. He takes off in his vintage biplane and is pursued by Myerson in the chopper. He evades Myerson's pistol shots for a while, but the plane is hit and suddenly explodes over the Channel. Later, from the cliff top, while looking down at the plane's scattered offshore wreckage, Myerson concludes that Kendig is dead. Cutter, however, ruefully remarks "He better stay dead", silently appreciating that the escape attempt was a Kendig ruse, his endgame all along.
The custom alterations made to the biplane also included a remote control device. Kendig walks away from an old airfield shack and drives away with Isobel for a long stay in the south of France. Months later, the explosive memoir has become a bestseller, and Kendig buys a copy in a bookstore dressed in a Sikh disguise. Isobel admonishes him for his intrigues and disguises, and they walk out together, book in hand.
The film music includes many pieces by Wolfgang Amadeus Mozart. Notable examples include the aria "Non Più Andrai" from the opera The Marriage of Figaro, the andante movement from Eine kleine Nachtmusik, the first movement of Mozart's Piano Sonata No.11, K331 (best known for the third movement, the Rondo alla turca), the Posthorn Serenade, K320 and a Rondo in D, K382.
Hermann Prey's singing of "Non Più Andrai" highlights the antics of the old biplane as Myerson is shooting at it. The song tells how Cherubino ("little baby"), going into the army, will no longer be a dainty favorite, just as 5-foot-7 Myerson is going to lose his power at the CIA. Also, the song describes bullets flying and even bombs exploding.
There is also the aria "Largo al Factotum" from the opera The Barber of Seville by Gioachino Rossini. Matthau sings this as he passes a border checkpoint. The words to the aria explain how everyone is looking for the barber, and he moves fast like lightning.
Kendig has the aria "Un Bel Dì Vedremo" ("One Beautiful Day") from Madame Butterfly by Giacomo Puccini playing loudly on the stereo as the FBI and CIA shoot up Myerson's wife's house. The operatic contrapunto adds a surreal air of ironic justice to the events as Madame Butterfly sings how she will hide from her husband.
Matthau, who had a personal fondness for opera, is said to have selected the soundtrack himself. The director said however that conductor Ian Frasier found many of the Mozart pieces that fit the movie.
The credits also list "Once a Night" written by Jackie English and Beverly Bremers. This is the blaring song playing at the bar "The Other End" where Matthau goes to arrange his flight from Georgia.
There are a number of small but notable differences between the novel and the film. Most significant are the endings; in the novel, Kendig fakes his own death using a recovered body from a Paris street and includes all copies of his expose's manuscript, ensuring it will never actually be published. In the film his escape airplane explodes in mid-air just as it heads over the English Channel and no body is recovered, and his expose is successfully published to great success. Both works include a knowing nod by Cutter that Kendig is alive but will hopefully stay dead. The Von Schoenenberg character is added in the film, while in the novel, Kendig has feelings for a hired pilot, which proves to him that he will find a new life outside of spycraft.