Doc Levy (Roy Scheider) is an American secret agent who has been running interference between the U.S. government and escaped Nazi war criminal Szell (Laurence Olivier). Believing that Doc has stolen a valuable cache of gems, Szell emerges from his South American hiding place and heads for New York. He has Doc killed, then kidnaps Doc's in-the-dark brother, Babe (Dustin Hoffman). Repeating the phrase "Is it safe?" over and over, Szell, a onetime concentration camp dentist, tries to extract information from Babe by performing sadistic "oral surgery" upon him. Babe, who still doesn't know about the gems, escapes, breaking his own self-imposed rule of nonviolence to defend himself against his pursuers and gearing up for sadistic revenge. ~


The film was a financial and critical success. Olivier's performance was particularly praised: he was nominated for an Oscar for Best Actor in a Supporting Role and he won a Golden Globe in the same category.
Dr. Szell was ranked as villain #34 on the American Film Institute's "100 Years... 100 Heroes and Villains" list. The film itself was ranked #50 on the "100 Years...100 Thrills" list. Both the novel and film contain a graphic depiction in which Szell tortures Babe by first probing a cavity in one of Babe's teeth with a curette, and later drilling into another tooth, without anesthetic, while repeatedly asking the question, "Is it safe?" The quote "Is it safe?" was ranked #70 on the "100 Years...100 Movie Quotes" list. The dental torture scene was named #66 on Bravo's 100 Scariest Movie Moments. The torture scene has been described as one of the most frightening sequences in film.[8] Critics have remarked on the high level of talent and classiness.[10]
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. Schlesinger said that he "is definitely someone that you can root for. The film is about his survival in a grim and hostile world. In our present age of anxiety we can all identify with characters who are not trying to get ahead but simply to survive."