- "You don't know who you are. What you've become, since the incident."
Leonard Shelby was an insurance investigator who, after being attacked by a burglar, suffered from anterograde amnesia.
Shelby was from San Francisco, and married Catherine Shelby. The two lived together, and he would often tease her about re-reading her favourite novel. In the course of his job, Leonard was called out to investigate Sammy Jankis, who had developed short-term memory loss due to a car accident. He suspected something strange about Jankis, so ordered a doctor to carry out some conditioning tests. When these did not produce results, Leonard ruled that Jankis's condition was mental, not physical, and he was not eligible for an insurance payout. Leonard got a promotion, but Sammy's wife came to his office distraught, asking if there was a chance Sammy could regain his memories. Leonard told her he thought that Sammy should be physically capable of doing so - he found out later this caused Mrs Jankis to go home and trick Sammy into killing her.
Later, one night Leonard woke to find his wife's side of the bed cold. He heard muffled screams coming from the bathroom, so drew a gun and burst in. He found an intruder raping his wife under a shower curtain, so shot the man, but another assailant hit him from behind, knocking him unconscious and causing anterograde memory loss. His wife did not survive the assault. Leonard got a hold of a police report, and set off to track down his wife's killer.
Teddy claimed that Sammy Jankis never had a wife, and was faking his amnesia condition. When Leonard investigated him he exposed him as a con man. After the attack took place, Leonard's wife survived, but could not cope with Leonard's condition. She tricked Leonard into killing her by injecting her with too much insulin, and then Leonard was put into a mental institution. At some point Leonard got out, believing that his wife had been killed in the assault, and Teddy gave him the police report to help track down the killer. They eventually found him, killed him, and Teddy took a picture of Leonard. However, Leonard did not remember, and set out again to find the killer, not remembering he had already found him. He removed several pages from the police report, to give himself a puzzle he could never solve. Teddy followed Leonard from town to town, in order to limit the damage he was doing.
Hunting John G.
The phone call
At some point later, Leonard arrived in a town and checked into the Discount Inn. Burt, on reception, noticed Leonard taking a picture of the place, and called his boss Jimmy Grantz. Jimmy met Leonard and came to know him as "the memory man". While in his room, Leonard received a call from Teddy, and began to explain about his condition and Sammy Jankis. While doing this, he began preparing to tattoo a fact onto his leg: "Fact 5: Access to drugs". However, Teddy convinced him that John G. (the name of his wife's killer) was a drug dealer. Leonard changed his tattoo accordingly and wrote it on his leg.
Leonard then discovered a tattoo on his arm stating "never answer the phone". Panicking, Leonard hung up and barricaded himself in his room. Someone then slipped an envelope under his door, containing a picture of Leonard smiling and pointing at his heart. Reluctantly Leonard took the man's call, and agreed to meet him downstairs. He went to the lobby and met Teddy, who claimed to be a police officer. He took a photo of Teddy, writing his name and number on the bottom. Leonard then set off for an abandoned barn, where John G. would be waiting.
Jimmy Grantz then arrived, and Leonard beat and strangled him to death. While transporting him to the basement, Jimmy whispered the words "Sammy Jankis". Thinking he had killed the wrong man, Leonard panicked and ran outside. He then saw Teddy who had just arrived, and demanded to know what was happening. Teddy explained that Leonard had already got his revenge, and now he just needed someone to believe was John G. in order to give his life purpose. Leonard refused to believe it, and wrote "Don't believe his lies" on Teddy's photograph. He then wrote a note that Fact 6 would be Teddy's license plate, and took Jimmy's car and clothes. He drove off, leaving Teddy alone.
While driving away, Leonard spotted a tattoo shop, and went in to get his latest fact etched on his skin. While the tattooist was at work, Teddy appeared wanting to speak with Leonard. He told him to change his clothes and get out of town, explaining that he was a police snitch. Leonard, looking at his polaroid of Teddy, decided not to "believe his lies", and climbed out of the window and went back to his car. He found a beermat in the glove compartment from Ferdy's bar, with a note from Natalie to "come by after".
He drove to Ferdy's and saw Natalie emptying the bins. She initially mistook him for Jimmy, but he followed her inside and asked for a beer. She poured a beer, but first got all the men at the bar including Leonard to spit in it. She waited until he sat down before serving the beer to him, to test his amnesia. Leonard drank the barbed drink, but Natalie got him another one before taking Lenny back to her house.
At Natalie's house, Lenny got out his police report and explained about his wife's killing. Natalie told him he could stay at hers for a while, and she left to go back to work after Lenny took a picture of her. However she quickly returned, saying associates of Jimmy were looking for her. She demanded Leonard deal with them, before starting to insult his wife. He told her to calm down, but she goaded him, telling him she was going to use him and there was nothing he could do. Angry, Lenny beat her up. She then left, and Leonard scrambled to find a pen to write down what had happened. However Natalie had hidden all of the pens, and returned just as Leonard's memory blanked again.
Natalie then explained that Dodd, one of Jimmy's associates, had beaten her up because of the missing money. Leonard then offered to take care of Dodd, and Natalie wrote his details down. Leonard left, to find Teddy waiting in his car. Teddy told him that Natalie was trying to use him, and that she was into drugs. He got Leonard to write "Do not trust her" in different handwriting on Natalie's picture, but Leonard crossed it out as soon as Teddy was gone. Teddy also gave Leonard the name of the Discount Inn, where he could stay.
Leonard checked into the Discount Inn, where Burt rented him another room on top of the one he already had. He called up Amazon Escorts and ordered a blonde call girl. When she arrived he gave her some items of his wife's, and asked her to leave them around the room before going to bed with him. He also asked her to slam the bathroom door after he was asleep. She did this, and Leonard woke up believing his wife was still alive. He then opened the bathroom door to find the woman snorting cocaine, so asked her to leave.
He then gathered all of his wife's belongings and drove to a wasteland where he burned it all. As he did, he remembered his wife using the different items, and realised that he had probably tried this before and burnt truckloads of his wife's belongings. He realised he would never get over her, due to his memory loss. As morning broke, he got in his car and drove away.
As Leonard drove away, he began being tailed by Dodd who recognised Jimmy's car. He pulled over and Dodd drew a gun on him, shooting out one of his car windows. Leonard ran through a caravan park, losing his memory during the chase and becoming confused. He then discovered his note with Dodd's details on, and decided to make his way to the Monterest Inn where Dodd was staying.
He broke into Dodd's room (after first breaking into the wrong room), and got a bottle of whiskey to use as a weapon. As he waited his memory faded again, and he woke up not knowing where he was. He took a shower, then Dodd returned and found him. The two struggled, before Leonard hit him with the bottle, knocking him out. Leonard tied him up in the cupboard, and phoned Teddy to deal with Dodd. He then fell asleep on the bed.
As Leonard woke, he discovered Dodd in the cupboard just as Teddy arrived. He showed Teddy the man in the cupboard, then realised that he wasn't in his room. They decided to drive Dodd out of town and threaten him not to come back. Leonard then wanted to find out what was going on, so drove to Natalie's house. He asked her who Dodd was, and she told him not to worry. He became stressed, thinking someone was setting him up, but she calmed him and spoke about losing her boyfriend. They slept together, and in the night Leonard wrote on her picture that she had lost someone, and would help him out of pity.
When he woke, Natalie (Nattie) told him she would talk to her friend at the DMV and trace his licence plate. They arranged to meet and Leonard left, but not before leaving his room key and putting on her shirt by mistake. As he got in his car, Teddy arrived and they got lunch together. Teddy told him he thought someone was setting him up, but Leonard ignored this and realised he had lost his key.
Back at the Discount, Leonard had Burt open his room to find his key. Lenny then realised Burt was ripping him off by renting him two rooms, but found his note about meeting Natalie so rushed off to the Chy Grill. She gave him back his key, and gave him a file with details of the owner of the licence plate on his arm. She also gave him details of the building that Jimmy used to deal out of, as a quiet spot to kill John G.
Leonard then washed his hands, discovering his Sammy Jankis tattoo. He then asked a waiter to direct him back to the Discount Inn, where he consulted his chart and Natalie's information to work out that Teddy was John G. He wrote "He is the one. Kill him." on his picture of Teddy, before going down to reception and speaking to Burt. He explained about his condition to Burt before Teddy arrived, and the two drove off together.
Leonard drove to the building, not knowing why. He then saw on Teddy's picture that he was the man he was looking for. He pulled his gun on Teddy, who begged Lenny to look downstairs to see what he had done in the past. Leonard didn't listen, and shot Teddy in the head, killing him. He then took a picture of Teddy's corpse.