Christopher Nolan has cemented his status as one of our most consistently original and thought-provoking directors. Over the last 25 years, Nolan has delivered film after film that deftly balances mainstream appeal with eye-popping visuals, inventive narrative structures and special effects, and existential and/or philosophical themes. And it all started with his big breakthrough film: Memento, which marks the 25th anniversary this year of its US release.

(Spoilers below, but we’ll give you a heads up before the major reveals.)

The origins of Memento are now the stuff of Hollywood legend. Nolan’s brother, Jonathan, pitched him a story during a road trip about a man with anterograde amnesia who can’t form new lasting memories and yet is intent on tracking down and killing the man who raped and killed his wife. Nolan liked the idea, and Jonathan sent him a draft a few months later. (That draft would eventually become Jonathan’s short story, “Memento Mori,” published after the film’s release.)

Nolan decided it would be fitting, given the protagonist’s unique condition, to tell the story backward and wrote his own version of the screenplay. He envisioned Memento as an inversion of the Jorge Luis Borges short story, “Funes the Memorious,” whose protagonist is a man who cannot forget anything, no matter how small the detail—a neurological condition known as hyperthymesia.

The two brothers exchanged various drafts for a year before the screenplay caught the attention of executives at Newmarket Films, who optioned the film and gave Nolan a $4.5 million budget. Brad Pitt was Nolan’s first choice for the lead, but when Pitt declined the offer, Nolan decided to skip the A-listers and cast Guy Pearce, best known at the time for his roles in The Adventures of Priscilla, Queen of the Desert (1994) and LA Confidential (1997). Nolan had been impressed by Carrie-Ann Moss’ performance as Trinity in 1999’s The Matrix and cast her as the female lead. It was Moss who suggested her Matrix co-star, Joe Pantoliano, for the third lead role.