The Descent is one of our favorite modern horror films, packed with an underground cave's worth of characters we actually care about and taught claustrophobic tension. Here we'll take a look at 10 killer facts about The Descent.

The creatures are human

Related: Special Sneak Preview of The Descent Coming to 47 Movie Theatres

The mysterious creatures that stalk the group of spelunkers in The Descent aren't supernatural or extraterrestrial in origin. Writer/director Neil Marshall calls them "Crawlers," cave people who diverged from the rest of us at some point in the evolutionary chain. The actors playing the Crawlers stayed away from the main cast during production, to ratchet up the anxiety in the performances. The actresses didn't see the Crawlers in their final form till it was time to shoot their first scenes together. The creatures are referred to as "Crawlers" in the film's closing credits.

The classic influences

In an interview with IndieWire, Marshall said the idea to set a film in a cave came to him on a train ride. And he drew upon his own trip into a cave he took at age ten. A huge fan of filmmakers like Ridley Scott and John Carpenter, Marshall has spoken about the influence of a handful of films on the look and feel of The Descent. There's the claustrophobic confinement of Alien, the slow turn toward madness of The Shining, and the adventure gone wrong of Deliverance. There's a bit of The Thing in play as well, plus the overall H.P. Lovecraft themes of a "descent" into madness.

The "cave" isn't real

As anyone who knows anything about caving will attest, it certainly isn't without its hazards. Trying to mount a whole film production like this one inside of a real cave was a bit too daunting, so producers opted to build cave sets, instead. While the movie takes place in North Carolina, the sets were built just outside of London, at the legendary Pinewood Studios. Pinewood's esteemed history includes several James Bond films, Tim Burton's Batman movies, the Avengers films, and many Star Wars franchise entries. The movie's exterior shots were done in Scotland.

There is only one man in the film

Aside from the non-speaking extras in the hospital scene, Sarah's husband is the only man in The Descent. (Unless, of course, we count any of the Crawlers as "men.")

A nocturnal easter egg

Remember that classic scene in Predator 2 when Danny Glover boards the Predator's ship and sees the trophy case with a Xenomorph skull inside? When Sarah falls into the discarded bones from the Crawlers previous meals, there's a wolf skull, in a nod to director Neil Marshall's 2002 werewolf thriller, Dog Soldiers.

The original poster

The London bombings of July 2005 changed the course of the movie's marketing. Originally, posters for The Descent around England featured an image of a single woman screaming in a tunnel, with a quote declaring the film's "outright terror." The film's UK distributor made new posters with all of the female cavers standing together and fighting back. A representative said at the time, "That seemed to chime with the prevailing mood of defiance that set in the weekend after the bombs."

The American poster

The poster artwork for the 2006 U.S. release is based on a famous photograph of surrealist painter Salvador Dali, which itself features one of Dali's works. The same "Female Bodies as a Skull" was part of the poster art for The Silence of the Lambs.

No happy ending

Leave it to the doom and gloom of jolly ole' England that gave us legendary mope icons like Morrissey and The Cure. The original UK version of The Descent ends with Sarah still trapped, as the creatures close in, having only dreamt of her escape. Test audiences in America were super bummed, so the ending was altered, cutting away before we see she's still trapped, letting Yanks think she survived. Marshall likened the American ending to The Texas Chainsaw Massacre, quipping to Entertainment Weekly at the time, "Just because she gets away, does that make it a happy ending?"

The cavers may be the villains

In a 2006 interview with KPBS, Neil Marshall explained, "This isn't about six cavers being attacked by savage monsters, this is a film about a happy society of savage monsters being attacked by these girls because they kind of mete out as much terror and pain as the Crawlers do." Ultimately, The Descent is a meditation on what people are capable of doing in order to survive. As Neil added about his characters, "their regression and descent into savagery, they become primal. They become like cave women at the end of the film because their instinct for survival is so strong."

Marshall didn't want a sequel

Editor Jon Harris, who had worked on the first one, directed 2009's The Descent 2. Although he's credited as an Executive Producer, Marshall wasn't too keen on there being a follow-up. When asked whether there'd be a third, Marshall told an interviewer in 2016, "The Descent was never intended to have a sequel, I don't think the story warrants a sequel, but there is a sequel, so make of it what you will."