The Descent features underground creatures, known as crawlers, which could certainly make the creepy movie monster hall of fame, but one theory suggests the movie’s real killer lies in its protagonist, Sarah (Shauna Macdonald) instead.

Following the world of spelunking, Neil Marshall’s The Descent places its characters into a tense situation right out the gate and then adds monsters to the mix. Claustrophobic camera angles heighten the fear felt by the characters, producing a movie best described as disturbing. The Descent was terrifying before the crawlers were introduced, using the atmosphere of underground caves and tunnels to create tension; the horror movie's bloodthirsty antagonists were only icing on the cake.

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The cave exacerbates Sarah’s extreme emotional strain; she is still grieving the death of her husband and child, and fighting with friend Juno (Natalie Mendoza). Between geographic and emotional burdens, tensions run high. It would be easy for Sarah to snap even without the presence of terrifying humanoid monsters.

The Descent Theory: Sarah Hallucinated The Crawlers

The potential for hallucinations is seeded early in the movie, when Rebecca (Saskia Mulder) mentions the “dehydration, disorientation, claustrophobia, panic attacks, paranoia, hallucinations, visual and aural deterioration,” that can come from spelunking. Audiences know Sarah hallucinates during her time in the cave. Depending on which ending one chooses to watch, these hallucinations vary in extremity; either a full escape montage or the visage of her dead friend. In fact, Marshall mentioned on the movie’s cast commentary that the original cut includes a scene of a crawler appearing in one of Sarah’s nightmares. This hints that the crawlers were intended to be ambiguous, as this scene would cement the idea that they were within her long before she went into the cave.

Sarah is the first to see a crawler, which can mean one of two things. She could have just completely invented them as an excuse to justify her friends’ slaughter. The other possibility is that there really are crawlers in the cave, but they are not the violent creatures we see onscreen. The initial crawlier could have been a source of inspiration. Sarah sees something monstrous, so she projects herself on it.

The Descent Is All About Sarah’s Descent Into Madness

The Descent

Sarah, who expected the descent to be a day trip, is unexpectedly off her medication. The crawlers could be an extension of her own loss of touch with reality. Horse Girl uses similar techniques to embed horror; the loss of clarity is foretold, but it's still difficult for audiences to discern truth from hallucination. Throughout The Descent, Sarah is seen killing two of her friends, so audiences know she is capable of violence, both as an act of mercy and vengeance. She condemns Juno to death amid a swarm of crawlers. If the crawlers are a projection of Sarah’s self, then that swarm could have been her own angry mind taking revenge for Juno’s affair with Sarah’s husband.

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Some fans have pointed out the parallel between the five crawlers Sarah kills onscreen and her five friends. The relationship between Sarah’s mental deterioration and the number five is solidified through the hallucination she has of her daughter holding a cake with five candles. In her final hallucination, the candles number six, which could symbolize the end of Sarah as she knew herself. Her friends are literally dead, but her descent into madness has left her figuratively destroyed.

It is worth noting that Holly (Nora-Jane Noone), the first to die, is killed in full sight of all five women. If Sarah was really the culprit, Juno would be less inclined to help her than she actually is. A possibility to explain this is that some horror of the deep really did kill Holly. It doesn’t even have to be a crawler. By that point in The Descent, Sarah had already seen one and could have just been projecting the image of crawlers onto whatever killed Holly. Holly’s death was Sarah’s breaking point; she is almost given cosmic permission to enact her hurt and pain by the barbarity she witnesses.

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