Memento is a 2000 American neo-noir psychological thriller film written and directed by Christopher Nolan, and produced by Suzanne and Jennifer Todd. The film's script was based on a pitch by Jonathan Nolan, who wrote the 2001 story "Memento Mori" from the concept. Guy Pearce stars as a man who, as a result of an injury, has anterograde amnesia (the inability to form new memories) and has short-term memory loss approximately every fifteen minutes. He is searching for the people who attacked him and killed his wife, using an intricate system of Polaroid photographs and tattoos to track information he cannot remember.
The film is presented as two different sequences of scenes interspersed during the film: a series in black-and-white that is shown chronologically, and a series of color sequences shown in reverse order (simulating for the audience the mental state of the protagonist). The two sequences meet at the end of the film, producing one complete and cohesive narrative.
Memento premiered at the 57th Venice International Film Festival on September 5, 2000, and was released in the United States on March 16, 2001. It was acclaimed by critics, who praised its nonlinear narrative structure and motifs of memory, perception, grief, and self-deception, and it earned $40 million over its $4.5 million budget. Memento received numerous accolades, including Oscar nominations for Best Original Screenplay and Best Film Editing. The film is now widely regarded as one of Nolan's finest works and one of the best films of the 2000s. In 2017, the United States Library of Congress deemed the film "culturally, historically, or aesthetically significant" and selected it for preservation in the National Film Registry.
The film starts with a Polaroid photograph of a dead man. As the sequence plays backward, the photo reverts to its undeveloped state, entering the camera before the man is shot in the head. The film then continues, alternating between black-and-white and color sequences.
The black-and-white sequences begin with Leonard Shelby, a former insurance investigator, in a motel room speaking to an unseen and unknown caller. Leonard has anterograde amnesia and is unable to store recent memories, the result of an attack by two men. Leonard explains that he killed the attacker who raped and strangled his wife Catherine, but a second clubbed him and escaped. The police did not accept that there was a second attacker, but Leonard believes the attacker's name is "John G" or "James G". Leonard investigates using notes, Polaroid photos, and tattoos. Leonard recalls Sammy Jankis, another anterograde amnesiac, from his insurance industry days. After tests confirmed Sammy's inability to learn tasks through repetition, Leonard believed that his condition was at best psychological (and perhaps faked) and turned down his insurance claim. Sammy's distraught wife repeatedly asked Sammy to administer her insulin shots for her diabetes, hoping he would remember and would stop himself from giving her a fatal overdose. However, Sammy continued to administer the injections, and his wife died.
The color sequences are shown reverse-chronologically. In the story's chronology, Leonard self-directively gets a tattoo of John G's license plate. Finding a note in his clothes, he meets Natalie, a bartender who resents Leonard because he wears the clothes and drives the car of her boyfriend, Jimmy Grantz. After understanding Leonard's condition, she uses it to get Leonard to drive a man named Dodd out of town and offers to run the license plate as a favor. Meanwhile, Leonard meets with a contact, Teddy, who helps with Dodd, but warns about Natalie. Leonard finds that he had previously annotated his Polaroid of Teddy, warning himself not to trust him. Natalie provides Leonard with the driver's license for a John Edward Gammell, Teddy's full name. Confirming Leonard's information on "John G" and his warnings, Leonard drives Teddy to an abandoned building, leading to the opening, where he shoots him.
In the final black-and-white sequence, prompted by the caller, Leonard meets with Teddy, an undercover officer, who has found Leonard's "John G", Jimmy, and directs Leonard to the abandoned building. When Jimmy arrives, Leonard strangles him fatally and takes a Polaroid photo of the body. As the photo develops, the black-and-white transitions to the final color sequence. Leonard swaps clothes with Jimmy, hearing him whisper "Sammy". As Leonard has only told Sammy's story to those he has met, he suddenly doubts Jimmy's role. Teddy arrives and asserts that Jimmy was John G, but when Leonard is undeterred, Teddy claims that he helped him kill the real attacker a year ago, and he has been using Leonard ever since. Teddy points out that since the name "John G" is common, Leonard will cyclically forget and begin again and that even Teddy himself has a "John G" name. Further, Teddy claims that Sammy's story is Leonard's own story, a memory Leonard has repressed to escape guilt.