One of the best thriller.

Rating: 10/10 (1 July 2016)

The film 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 sequences of black and white chronologically and color reverse- chronologically interspersed.
The black-and-white sequences begin with Leonard Shelby (Guy Pearce) in a motel room speaking to an unnamed telephone caller who is not shown on- screen. 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 (Jorja Fox), 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 or James, with a last name starting with G. Leonard conducts his own investigation using a system of notes, Polaroids, and tattoos. As an insurance investigator, Leonard recalls one Sammy Jankis (Stephen Tobolowsky), also diagnosed with the same condition. Sammy's diabetic wife (Harriet Sansom Harris), who was not sure if his condition was genuine, repeatedly requested insulin injections to try to get him to break his act. He overdosed her, falling into a coma and dying as a result.
The color sequences are shown reverse-chronologically. In the story's chronology, Leonard gets a tattoo, based on self-directed instructions, of John G's license plate. 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 (Callum Keith Rennie) 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; Leonard finds a photo written to not trust him, however. Natalie provides Leonard the driver's license, which shows a John Edward Gammell, Teddy's full name. 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.