In terms of lockdown movies, it doesn’t get much more locked down than Saw: two men (Cary Elwes and Leigh Whannell) wake up chained to pipes in the kind of bathroom you only usually see at the bottom of an Expedia search (or top depending on what you’ve sorted by).

We’ve all been there.

This no-nonsense nasty from 2004 introduces Jigsaw (Tobin Bell), who joins the pantheon of horror villains with very specific MOs: SE7EN concerns a string of murders based on the deadly sins; You Can’t Stop the Murders sees a killer targeting the professions represented by the Village People; Jigsaw tests his victims’ will to survive to teach them the value of human life, which may have made sense to him at one point but has clearly gotten out of hand. Much like the Saw franchise.

In the wake of countless torture porn sequels and deadly puzzle imitators, it’s easy to lose sight of Saw‘s stripped-down genius. The simple setup sparks a perfectly structured series of flashbacks that constantly reframe the bathroom action, like an ultraviolent episode of Lost (Michael Emerson and Ken Leung also feature). Considering the gross-out direction the franchise would take, it’s surprising to note the absence of gore here; everything is suggested using jittery jump cuts, spiralling camera manoeuvres and sickly green filters.

That’s not to say the film shows restraint, opting for an everything-including-the-bathroom-sink approach to visuals, plot twists and acting; The Princess Bride‘s Elwes is so hammy he’s easily confused for the character who wears a pig mask, opposite a more deliberately funny performance from the movie’s writer Whannell. Danny Glover plays a bumbling detective who begs the question of why all the characters are willing to kill strangers but so reluctant to shoot bad guys.

Also surprising is that this film is directed by James Wan, who would go on to do to the horror genre what Jigsaw does to his victims (although his sea sickness-inducing direction does make him the perfect choice to make a terrible film about Aquaman). Compared to his subsequent Conjuring–type output, Wan’s debut feature relies on breakneck pacing, narrative puzzles and low-budget resourcefulness instead of yawnted houses and jump snores. Or maybe he was just ripping off David Fincher.

Soon to make him the biggest name in horror, Wan’s marketing smarts are evident in the iconic doll design, “I want to play a game” catchphrase and “Dare you see Saw?” tagline. And then there’s the ending, which tips it from a great horror movie into a bloody classic. Where did it all go Wan?