The Descent is one of the best horror movies of the ’00s, and remains a thoroughly terrifying watch years after its release. Its story follows a group of spelunkers who find themselves lost in a complex cave system and hunted by sightless creatures deep below the Earth. However, one particularly dark theory about The Descent reframes its entire narrative, making it somehow even scarier.

One year after the tragic death of Sarah’s husband and daughter, her group of thrill-seeking friends take her on a spelunking adventure to an unexplored cave system to rekindle their lost friendship and support Sarah during her ongoing battle with mental illness. Shortly after entering, the friends are trapped inside by a collapse, and forced to explore the caves in the hope of finding an exit. While inside, they find themselves hunted by vicious sightless monsters describe as “crawlers“, and their adventure quickly becomes a nightmare as they fight to survive.

The Descent ends with Sarah being the lone survivor of the ordeal, although the film technically has two different endings. One ends with Sarah escaping the cave but hallucinating her friend Juno sitting beside her. The other has a final scene in which Sarah wakes up still trapped in the cave after this hallucination, revealing that she was only dreaming of her escape. However, one particularly dark theory about The Descent makes its ending much more disturbing: that the creatures were all a hallucination, and that Sarah herself is responsible for the murder of her friends.

How The Dark Theory About Sarah Changes The Descent

Sarah in The Descent (2005)

The theory is actually relatively simple. The Descent explains that Sarah has been having trouble with hallucinations, and she also discovers that her best friend Juno had been sleeping with her late husband. The theory believes that the stress of being trapped in the cave, combined with her knowledge of Juno’s betrayal and her continuing grief all prompted a psychotic break in which she brutally attacks and kills her friends.

In this theory, the monsters are Sarah’s way of rationalizing her actions, representing her mental illness. Additionally, their blindness could represent her blind rage or her inability to see her husband’s infidelity. The theory also fits with her later actions – she wounds and leaves Juno for dead, and euthanizes Beth. Of her five friends, she’s shown killing two, so it’s not too far fetched to think she hallucinated creatures committing the other murders.

Of course, it’s a complex rationalization, but the film itself doesn’t rule out the theory. Sarah finds herself covered in blood after falling into a pool, which again could be her mind hallucinating an explanation for why she’s coated with others’ blood. The notion that Sarah’s journey into the cave actually represents her descent into madness is ultimately at the film’s heart anyway, but this dark theory makes The Descent a much more literal representation of mental illness.