Leonard (Guy Pearce)’s Timeline and Summary
- Leonard is an insurance claims investigator. One of the cases he works involved a man named Sammy Jankis
- Speculative: Leonard exposed Sammy as a fraud who was feigning anterograde amnesia.
- Speculative: Sammy, while supposedly physically capable of creating new memories, could not. Leonard gets a promotion by turning the claims on the grounds that Sammy was not covered for mental health. When Sammy's wife asks for his personal opinion, Leonard tells her Sammy is physically capable of creating new memories
- Leonard defends his wife who is being attacked by two men, but suffers a blow to the head… which causes anterograde amnesia
- Speculative: Leonard kills his wife by overdosing her on insulin as she tests his ability to create new memories
- Leonard seeks revenge on his wife's assailant with the help of a policeman named Teddy, killing targets Teddy selects with the name John G… the first of which is supposedly the actual culprit.
- In the present, Leonard is holed up in a hotel, giving himself a new tattoo and talking to Teddy on the phone about his system and about Sammy Jankis.
- Teddy convinces him to meet him in the lobby because he has located the person they've been searching (who is actually Jimmy Grantz).
- Leonard kills Jimmy but realizes he's the wrong dude. Teddy is forced to spill the beans about what's actually been going on.
- Leonard chooses to frame Teddy as John G. and thereby stop his cycle of lies.
- Leonard gets a tattoo of Teddy's license plate and then heads to Freddy's Bar to meet Natalie.
- Natalie takes him into her home and makes Leonard mad, so he hits her. She then convinces him that Dodd did it and he offers to find Dodd and make him pay.
- In the meantime, Leonard orders a prostitute and burns his wife's things.
- Dodd finds Leonard and Leonard barely escapes… and then attacks Dodd from within his own shower.
- He calls Lenny, who helps him get rid of Dodd before Leonard returns to Natalie wondering what happened.
- Leonard wakes up and grabs some grub with Teddy. Then he meets up with Natalie at a diner, and she gives him the license plate info that incriminates Teddy.
- Leonard meets Teddy in the Discount Inn lobby. He takes him to the abandoned building where he killed Jimmy, and shoots Teddy.