Screening at Sundance (Dramatic Competition). Dir: Christopher Nolan. US. 2000. 113mins.

Not content with the challenges raised by making a film about a memory-deficient character who has to work out where he is every time he wakes up, Nolan has complicated life further by telling the story of Memento backwards, cut up into narrative chunks that last as long as the character's memory - with extensive, but not obtrusive, use of first-person voice over.

It all sounds like a recipe for high-concept pretension, yet the narrative tension is maintained expertly throughout and the end result is gripping and intellectually satisfying. Memento is the sort of film that gives rise to long post-screening discussions. It has already performed strongly on limited release in the UK and should continue doing so in sophisticated urban markets worldwide.

Amnesia thrillers were big in the 1940s and 1950s. UK film-maker Nolan's second feature (after the small but interesting Following) is a stylish revisitation of the genre - although as the hero never tires of repeating, it's not exactly amnesia that he suffers from - it's short-term memory loss. In other words, Leonard Shelby's memories fade after about 10 minutes, and if he wants to keep track of names, faces and information, he has to make a note of them.

He does this in three main ways: taking Polaroids of the people he meets, writing notes (sometimes on the Polaroids) and, when something is particularly crucial, having it tattooed on his body. Given his handicap, Leonard is the last person who should be conducting an investigation, but that is just what he's doing: looking for the man who raped and killed his wife and who took away his ability to make new memories. There are even moments of black humour, such as when Leonard finds himself running in a trailer park and cannot remember if he's chasing or being chased. The other guy fires a gun at him and the penny drops.

Guy Pearce plays the lead role with the right mixture of determination and fazed humility. That the ending leaves too many questions unanswered will, if anything, only boost the film's word-of-mouth appeal. Nolan has said that this would be "a great film to see on DVD" because of the chance the new medium offers to rewind, review and check; or even to view the film in chronological order. Although he also makes it clear that Memento was not made with DVD in mind, his comment raises interesting issues of the extent to which the DVD outlet can be expected to affect film structure in the future.

Prod co: Team Todd. Exec prod co: Newmarket. Int'l sales: Summit Entertainment. Prods: Suzanne Todd, Jennifer Todd. Exec prods: Aaron Ryder, Will Tyrer, Chris Ball. Scr: Christopher Nolan, based on the short story by Jonathan Nolan. Cinematographer: Wally Pfister. Ed: Dody Dorn. Main cast: Guy Pearce, Carrie-Anne Moss, Joe Pantoliano, Jorja Fox, Stephen Tobolowsky, Harriet Sansom Harris.