Friendship is a powerful thing. It brings people together in the best and worst of times. It can even be a replacement for family. Friends know your darkest secrets. But sometimes, friendship can be horrifying. Neil Marshall’s 2005 horror film, The Descent, is a psychological rollercoaster that reveals the horrors of friendship and the secrets we keep from those closest to us.

The Descent follows a group of women going on a spelunking trip in the middle of nowhere. They are a group of intrepid cavers, all with their own expertise and experience diving deep into the Earth. However, this particular trip is important: it is meant to support their friend, Sarah (Shauna Macdonald), who lost her daughter and husband only a year prior. Juno (Natalie Mendonza) organizes the trip to bring them all together, picking a cave system that is supposedly easy going. However, as a tunnel caves in, the group soon discovers Juno picked an unknown system with the intention of naming it after Sarah’s deceased daughter. That’s not the only horrifying thing. In this cave lurk pallid, humanoid creatures called “Crawlers” that have a taste for human flesh. The group of friends must struggle to survive as they’re hunted down one by one. But it is not just the monsters that are terrifying.

The Descent is lauded by some as a contemporary horror classic. Writer Steven Gerrard calls it “a superior British horror film” in his book The Modern British Horror Film. The film is an accomplishment in creating crushing feelings of claustrophobia and terror on a limited budget with a cast of unknown, yet talented, actors. It is a film grounded in female friendships but then tears them apart, literally. As Roger Ebert says in his review, “These women are straining the limits of their muscles and bones, their friendships, and their core beliefs about who they are.”

This friend group is made up of six women, all from different backgrounds and with different relationships to one another. The only uniting factors are Sarah and a love of adventure sports, particularly spelunking. Importantly, the group is made exclusively of women with no romantic relationships, making the trip simply platonic — all feelings towards one another are out of friendship rather than romance. This again puts friendship in the film’s foreground.

Before they even venture into the cave, it’s established that Juno is the group’s outcast. She is regarded with eye rolls and sarcastic remarks from the film’s beginning. In most friend groups, there is a black sheep — and Juno sticks out, from her type A attitude to her American accent. She is met with what seems to be slight disdain from those she considers friends. Setting her apart as an outcast also casts an air of suspicion around Juno — if she is met with such reactions from those who are close to her, what is she capable of?

Besides damning the group to a gruesome fate with her cave decision, it is also revealed that Juno was having an affair with Sarah’s husband, the deepest kind of a betrayal from a close friend. Juno tells Beth (Alex Reid), “Sarah wasn’t the only one who lost something in the accident.” In that moment, it is difficult to see what is more horrifying: the Crawlers or Juno’s betrayal. The horrors of the cave melt away and all that is left in two friends uncovering an ugly truth.

Besides trusting your friends, it’s also typically expected to believe your friends, even if what they say seems outlandish. This isn’t the case in The Descent. Sarah is the first to see the Crawlers but told that she is just seeing things. While they are in a dark cave and her eyes could be playing tricks on her, this also reflects attitudes towards Sarah as the Mad Woman. Sarah is set up as an Other due to the loss of her husband and daughter, and she’s treated as such. Sarah is regarded as something to be taken care of, something delicate that could break at any time. Instead of being supported by her friends, she is treated almost as a child, as someone that just needs looking after.

As it becomes apparent that Sarah wasn’t just seeing things and the monsters start crawling out of the walls, the group begins to split up. In horror films, it is seen as idiotic to split off from the group and wander off alone. That isn’t the case in The Descent. At first, this seems to be the ideal situation for relying on your strong, adventure-inclined friends to protect you in the dark from mutant humanoids. However, in The Descent, those friends are more of a detriment than support. A prime example is a contrast between sisters Sam, Rebecca and Sarah. Sam and Rebecca rely on each other as they try to hide from the Crawlers, only to have Sam’s watch go off loudly, bringing the monsters down on both of them. Rebecca is doomed by the actions of her sister. Again, what is scarier: the Crawler or the fact that your own friend, and sister, could lead to your death? It seems like an easy answer. But it a situation like this, it is terrifying that something as small as a cheesy plastic watch could be the instrument of their death.

Sarah, on the other hand, is able to protect herself, not worry about the noises of others and quietly avoid the Crawlers. While the trip has been about supporting her, it seems that it has had the opposite effect — rather than feeling empowered and supported by these friends, Sarah is able to better thrive on her own.

These horrors of friendship, from not believing one another to having sex with a friend’s husband, culminates in the death of Beth, Sarah’s closest friend. Beth is the one who has taken the most care of her and who is most invested in her healing. She is also the friend who is most suspicious of Juno’s relationship with Sarah’s husband. So, it seems almost poetic that Juno accidentally kills her in the typical “accidentally killing your friend thinking they are a bad guy” trope. Not only is it a fulfillment of the trope, it is another instance of not being able to trust your own friends. Juno is already not trusted, but now she is even more of a villain.

While The Descent is grounded in female friendship and showcases the power of women without the support of men, it also highlights the futility of teamwork in such a dire situation. Set in a place where friends are forced to be together in such a claustrophobic space, the horrors of the friends’ transgressions and suspicions can’t be escaped. Even with a pack of gargoyle-like creatures hunting them, some of the scariest scenarios are the ones between friends. In The Descent, a friend’s true nature comes to light in the darkest of places.

Mary Beth McAndrews (@mbmcandrews) is a freelance film writer with a love of all things horror based in Washington, D.C. She’s a contributor for Much Ado About Cinema and Nightmare on Film Street. Her hobbies include trying to get her friends to watch horror movies and annoying her cat.