Thomas Babington "Babe" Levy is a history student and distance runner who seeks to rehabilitate the memory of his father, who took his own life during McCarthyism.

Babe's brother Henry "Doc", under the guise of an oil company executive, is a government agent operating for a secret agency headed by Peter Janeway.

Doc is a courier for the transport of diamonds owned by Szell and kept in a safe deposit box in New York City.

Szell, having learned of his brother's death, secretly arrives in New York to collect the diamonds, and the couriers are mysteriously killed.

Babe is rescued by Janeway, who explains that Szell is in America to sell a cache of diamonds he had taken from Jews killed at Auschwitz.

Szell retrieves his diamonds, but as he attempts to leave the bank, Babe forces him at gunpoint to a pump house in the Reservoir.

Paul Cobley stated in The American Thriller: Generic Innovation and Social Change in the 1970s that Janeway "can be read as the impersonality of late capitalism [...] or a post-Foucaldian embodiment of the shifting locations of power", or "a representative of the vicissitudes of the market".

[11] Goldman was paid a reported US$500,000 (equivalent to $3.09 million in 2023) for the film rights to his novel, and to write a screenplay, before the novel had been published.

[15] Goldman says that John Schlesinger agreed to do the film only because he had just finished The Day of the Locust and was "terrified he was dead in Hollywood".

[16] Goldman says "all the stuff dealing with cities in crisis" in an original draft of the script was Schlesinger's idea although "Almost none of it made the finished film.

This is handled subtly in the movie (when Doc arrives in Paris, he calls Janeway on the phone and says, "Janie, I miss you.

[19] Goldman told an interviewer that he thought the new, more famous ending was "shit" because it left out two important plot clarifications.

In the novel, Babe resolutely leads Szell to Central Park and shoots him multiple times, subsequently lecturing him.

[19] Marathon Man was the second feature film production in which inventor-operator Garrett Brown used his then-new Steadicam, after Bound for Glory.

This new camera stabilization system was used extensively in Marathon Man's running and chase scenes on the streets of New York City.

In the usual telling of the story, Hoffman, a proponent of method acting, prepared for a scene in which his character had been awake for three days by doing the same himself.

"[21] In an interview on Inside the Actors Studio, Hoffman said that this exchange had been distorted; that he had been up all night at a nightclub for personal rather than professional reasons, and Olivier, who was aware of this, was merely joking.

[23] Stanley Kauffmann of The New Republic wrote, "While people said that the violence in Marathon Man was excessive, I was surprised: I had wriggled through that dental torture, but it hadn't seemed a pinnacle in a year during which I had seen two penises cut off and another penis nailed to a board—in films from France and Japan.

Astres étincelants, sung by Joseph Rouleau with the orchestra of the Royal Opera House, conducted by John Matheson, published on Decca Records).

The consensus reads: "Marathon Man runs the gamut from patient mystery to pulse-pounding thriller, aided by Laurence Olivier's coldly terrifying performance and a brainy script by William Goldman.

[34] Director Schlesinger said that Marathon Man was successful not only because it had elements of escapism, but also because the audience easily identified with Babe Levy.