It is 1950s New York City and Tom Ripley is a young man struggling to make a living, relying on his talents. His talents happen to be forgery, lying and impersonation. Whilst at a cocktail party playing the piano, he is approached my wealthy ship builder Herbert Greenleaf, who mistakes him for a young man who went to Princeton with his son Dickie, an impression he is given by the borrowed Princeton blazer Ripley is wearing. Greenleaf recruits Ripley to go to Italy with the task of persuading Dickie to return home to the United States. In return for this he will pay Ripley one thousand dollars. Despite never having met Dickie and never having attended Princeton, Ripley readily accepts.
Upon arriving in Europe Ripley meets Meredith Logue, a young, wealthy heiress to a textile empire. During their brief conversation Ripley impulsively represents himself as Dickie, commenting in a voice-over later that it is better to be a fake somebody than a real nobody. Shortly thereafter he fakes a chance encounter with the real Dickie and his fiancé Marge Sherwood, attempting to convince Dickie that they met at Princeton. Subsequently he visits Dickie and Marge disclosing that Dickie's father paid him to persuade Dickie to go home. Dickie is furious and suggests Ripley returns to America to inform his father he has no intention of going home. Rather than doing this, Ripley insinuates himself into Dickue's life, citing a mutual love of jazz. The two devise a scheme to con additional money from Greenleaf Senior by mailing regular letters staring that Dickie is vascilating and can likely be persuaded to return if Ripley remains in Italy and continues to apply pressure on him.
Whilst on an excursion to Rome Ripley meets Freddie Miles, a friend of Dickie's who barely conceals his contempt for Ripley. A local Italian girl whom Dickie had got pregnant drowns herself after he refuses to support her financially. This precipitates a downward spiral for Dickie and resenting Ripley's constant presence, which he finds suffocating. Ripley is becoming sexually obsessed with Dickie and also growing attached to the high-flying lifestyle his friendship with Dickie is affording him. Before Ripley returns to America Dickie invites Ripley on a sailing trip to San Remo where Dickie is house hunting. Whilst they are at sea Ripley suggests that he comes back to Italy the following year and becomes Dickie's housemate. Dickie informs Ripley he is going to marry his fiancé Marge which enrages Ripley so much he lashes out at him and hits him repeatedly with an oar, killing him. Panicking Ripley tries to conceal the murder by scuttling the boat with Dickie's body on board then swims to shore himself.
When the hotel concierge mistakes him for Dickie, Ripley realizes that he can assume Dickie's identity. He forges his signature, alters his passport and begins funding his lifestyle using Dickie's trust fund. He writes to Maege using Dickie's typewriter and convinces her he has left her. He creates an elaborate charade that maintains both his own and Dickie's identities, checking into two separate hotels as two separate identities, passing messages between hotel staff to make it appear Dickie is still living.this situation is greatly complicated when Meredith re-emerges as she still believes him to be Dickie.
Ripley rents a large apartment and spends Christmas alone having gifted himself many expensive presents. Meanwhile Freddie tracks Ripley down fully expecting to find Dickie. He is suspicious as the apartment is not furnished in Dickie's style whilst Ripley had adopted Dickie's hair style and mannerisms. As he is leaving Freddie meets the building's landlady and learns that she loves to hear piano music floating from the apartment where the man she calls Signire Dickie lives. Freddie knows that Dickie does not play piano and returns to the apartment to confront Ripley. Ripley attacks Freddie and kills him by hitting him over the head with a heavy statue.he carries the body to Freddie's car and drives our to the woods where he leaves Freddie's body on the ground and abandons his car.
Freddie's corpse is quickly discovered and Ripley's life becomes a cat-and-mouse game of avoiding both the police and Dockue's friends. He escapes capture and clears his name by faking a suicide note allegedly from Dickie and addressed to him. He moves to Venice and rents am apartment in his own name. Although Dickie's father trusts Ripley he hires a private detective called Alvin McCarron to investigate his son's death. Marge has always suspected that Ripley was involved on the death and confronts him after finding Dickie's rings in Ripley's bathroom. Ripley seems to be close to murdering Marge but is interrupted by their mutual friend Peter Smith-Kingsley who enters the apartment using the key Ripley gave him. McCarron, after unearthing some unsavory details about Dickie's past and tells Ripley that after learning this has dropped the investigation. McCarron will not be sharing his findings with the police and asks Ripley to do the same. In return Greenleaf intends to transfer a significant portion of Dickie's trust fund into Ripley's name. Marge is angry about this and accuses Ripley of involvement in Dickie's death before she is forcibly removed by Greenlwaf and McCarron.
Ripley and Peter, now in a romantic relationship, go on a cruise together it discover Meredith is also on board. Ripley realizes that he will not be able to prevent them from communicating and also realizes that Meredith will tell Peter he has been pretending to be Dickie. He cannot murder Meredith as she is with her family so he strangles Peter to death, sobbing whilst he does so. He returns to his cabin where he sits all alone.