Memento (2000)

Memento is a 2000 American psychological thriller and neo-noir film written and directed by Christopher Nolan, adapted from his younger brother Jonathan's short story, Memento Mori. The film starring Guy Pearce, Joe Pantoliano and Carrie-Anne Moss.

Plot: A backwards sequence is shown. It starts with the Polaroid photograph of a dead man. As the sequence plays backwards the photo reverts to its undeveloped state, entering the camera before the man is shot in the head. This is followed by interspersed black-and-white and color sequences, with the black-and-white sequences taking place chronologically before the color sequences. The black-and-white sequences begin with Leonard Shelby (Guy Pearce) in a motel room speaking to an unnamed caller. Leonard has anterograde amnesia and is unable to store recent memories, the result of an attack by two men. Leonard killed the attacker who raped and strangled his wife (Jorja Fox), but a second clubbed him and escaped. The police did not accept there was a second attacker, but Leonard believes he is called John with a last name starting with G. Leonard conducts his own investigation using a system of notes, Polaroid photos, and tattoos. As an insurance investigator, Leonard recalls one Sammy Jankis, also diagnosed with the same condition. Sammy's diabetic wife repeatedly requested insulin injections to try and trigger his memory, hoping Sammy would remember the previous dose. He did not and as a result she fell into a coma and died.

The color sequences are shown in reverse chronological order. Leonard gets a tattoo, based on instructions to himself, of the license plate of John G. Finding a note in his clothes, he meets Natalie (Carrie-Anne Moss), a bartender who resents Leonard as he wears the clothes and drives the car of her boyfriend, Jimmy. After understanding his condition, she uses it to get Leonard to drive a man named Dodd out of town and offers to run the license plate to help his investigation. Meanwhile, Leonard meets with a contact, Teddy (Joe Pantoliano). Teddy helps with Dodd, but warns him about Natalie; however, Leonard has written on a photo of Teddy to not trust him. Natalie provides Leonard the driver's license, which shows a John Edward Gammell, the real name of Teddy. Confirming Leonard's information on "John G" and his warnings, Leonard meets Teddy and drives him to an abandoned building, killing him as shown in the opening. In the final black-and-white sequence, prompted by the caller, Leonard meets Teddy in the motel lobby. Teddy is an undercover officer and has found Leonard's "John G", Natalie’s boyfriend Jimmy Grantz, and directs Leonard to the same abandoned building outside of town. When Jimmy arrives, Leonard strangles him and takes a photo of the body. As it develops the black-and-white transitions to color, thus beginning the color sequences. Leonard swaps clothes with Jimmy, hearing Jimmy whisper "Sammy". As Leonard has only told the story of Sammy to those he has met, he doubts Jimmy is the attacker.

–from wikipedia