Before delving into the story, it’s important to understand Memento’s unique narrative structure. The film employs a dual narrative technique, where one storyline unfolds in color and runs backward in time, while the other is presented in black-and-white and moves forward chronologically. This non-linear arrangement reflects the protagonist Leonard Shelby’s (Guy Pearce) condition—anterograde amnesia—which prevents him from forming new memories. The scenes are intentionally arranged to create a disorienting experience for the audience, culminating in a convergence of these two timelines at the film’s climax.
The story centers on Leonard Shelby, whom we first encounter taking a Polaroid photograph. As the scene unfolds in reverse, we watch the image fade from existence as it returns to the camera. The photo’s subject is John G, whom Leonard believes to be his wife’s murderer.
The narrative shifts to a black-and-white sequence where we find Leonard in his hotel room. After awakening, he makes a phone call during which he discusses his condition: anterograde amnesia. Unlike typical memory loss, Leonard’s condition specifically prevents him from forming new memories. He can only retain information for approximately 15 minutes before it vanishes, though his memories prior to the traumatic incident remain intact.
The catalyst for Leonard’s condition stems from a tragic home invasion. While investigating suspicious noises, Leonard discovered intruders attacking his wife, Catherine (Jorja Fox). The ensuing confrontation turned violent—though Leonard managed to shoot one assailant, a second attacker emerged from behind and knocked him unconscious beside his dying wife. In his last moments of clear memory, Leonard recalled the second attacker’s name: John G.
Upon regaining consciousness, Leonard immediately reported the second perpetrator to the police. However, when authorities found no evidence supporting the existence of this second attacker, frustrated Leonard resolved to pursue justice on his own, determined to find his wife’s murderer despite his debilitating condition.
To manage his condition, Leonard develops an intricate system of documentation using various tools: notepaper, pens, Polaroid cameras, and even tattoos. He meticulously records every significant moment before it slips away, including crucial facts about his wife’s death which he permanently inscribes on his skin.
In a black-and-white sequence, Leonard recalls his previous career as an insurance investigator and his encounter with Sammy Jankis (Stephen Tobolowsky). Sammy suffered from a similar inability to form new memories following an accident that damaged his hippocampus. His condition manifested in peculiar ways—while he could enjoy brief television commercials, longer programs proved impossible to follow due to his memory reset.
Sammy’s tragic story involves his diabetic wife (Harriet Sansom Harris) who struggled to accept her husband’s condition. To test Sammy’s memory loss authenticity, she repeatedly asked him to administer her insulin. Each time, having no recollection of previous injections, Sammy complied. This devastating test ended with her death from an insulin overdose while Sammy remained oblivious to his role in the tragedy.
The narrative shifts back to Leonard’s investigation where we meet Teddy (Joe Pantoliano)—a police officer working undercover who offers to help Leonard track down John G. This collaboration leads Leonard to Jimmy Grantz (Larry Holden), a drug dealer whom he believes is connected to his wife’s murder. In a climactic moment, Leonard executes Jimmy and photographs the aftermath with his Polaroid camera. As Jimmy dies, he mysteriously utters “Sammy,” hinting at deeper connections between their stories.
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The scene transitions to color as Leonard dons Jimmy’s clothes. Teddy arrives and delivers a shocking revelation: not only had Leonard already killed his wife’s murderer a year ago, but the story of Sammy Jankis is actually a reflection of Leonard’s own history, reconstructed and projected onto a fictional character. According to Teddy, Sammy was a creation of Leonard’s mind, and the wife who died from an insulin overdose was actually Leonard’s own wife, Catherine.
Disturbed by these revelations and feeling manipulated by Teddy, who has used him to eliminate drug dealers for his own gain, Leonard takes decisive action. He burns the photographs of both Jimmy and himself at the crime scene. He writes “don’t believe his lie” on Teddy’s photo and tattoos Teddy’s license plate number on his thigh, effectively setting up Teddy as his next target.
After killing Jimmy and tattooing this latest reminder, Leonard discovers a key chain in Jimmy’s clothes with an address that leads him to Natalie (Carrie-Anne Moss), Jimmy’s girlfriend. When Leonard arrives driving Jimmy’s car and wearing his clothes, Natalie is understandably confused. Upon questioning about Jimmy’s whereabouts, Leonard’s memory resets, leaving him unable to explain the situation. Intrigued by his condition, Natalie invites Leonard to her workplace, a bar.
To test Leonard’s memory loss, Natalie devises a disturbing experiment. She has various people, including herself and bar patrons, spit into a glass. Minutes later, when Leonard’s memory has reset, she offers him the contaminated drink, which he unwittingly consumes, proving the authenticity of his condition.
As time passes, Natalie pieces together that Leonard killed Jimmy. However, rather than reporting him to the authorities, she decides to use Leonard’s condition to her advantage. She enlists his help in dealing with Dodd (Callum Keith Rennie), a threatening figure connected to Jimmy’s drug operations. Leonard agrees to help, though his memory reset means he won’t remember making this promise.
The narrative then shifts to an intense car chase with Dodd pursuing Leonard through residential streets. The scene takes a darkly comedic turn when Leonard forgets he is being chased; in a moment of confusion, he even takes a shower while hiding from Dodd. Despite this memory lapse, the confrontation ultimately ends in Leonard’s favor; however, in a final ironic twist, he has to ask his defeated opponent’s name, having forgotten why they were fighting in the first place.
In a pivotal scene, Natalie provides Leonard with a file containing crucial information about his target, including the name John Gammell (Teddy) and a license plate number. She manipulates Leonard into believing that Teddy—whom he already distrusts—is the John he’s been searching for. After verifying that the license plate matches Teddy’s car, Leonard immediately departs while Natalie takes satisfaction in her successful manipulation.
The story culminates at the abandoned building where Jimmy was killed. Leonard lures Teddy to this location and executes him without hesitation, bringing the complex narrative full circle as it connects back to the film’s opening scene of Leonard photographing Teddy’s dead body.
This ending reveals the tragic irony of Leonard’s condition: his system of notes, photographs, and tattoos—intended to help him find justice—can be manipulated by others to serve their own purposes. His quest for vengeance becomes a tool that others use for their ends while his memory condition ensures he’ll never fully understand the truth of his actions.
