UNDERWATER*CUT TO THE CHASE*
Deep in the Mariana Trench is an underwater drilling station, the Kepler, run by Tian Industries. Engineer Norah Price (Kristen Stewart) narrates her feelings of losing track of time due to being down there as long as she has. Moments later, an earthquake strikes the station. Norah rushes with coworker Rodrigo Nagenda (Mamoudou Athie) to safety, being forced to leave several others trapped as water fills the area. A small explosion occurs and knocks Norah out.
After waking up, Norah and Rodrigo move forward to find evacuation pods. They find Paul Abel (TJ Miller) trapped under debris and free him while finding another dead man nearby. Soon, the three reconvene with Captain Lucien (Vincent Cassel) and biologist/engineer couple Emily Haversham (Jessica Henwick) and Liam Smith (John Gallagher Jr.). They find that the pods are all gone, but Lucien suggests they make their way to the nearby Roebuck station to find a way out. Despite Norah protesting that it’s risky, Lucien says it may be their only way out.
The crew dons pressurized suits to make their way to Roebuck. As they ride an elevator upwards, Rodrigo’s helmet cracks until it breaks completely and causes him to burst messily from the depressurization as the water comes in. As they move forward, Paul mourns and remembers Rodrigo. Norah looks on at a picture of her with her fiance.
Continuing to move on, Liam and Paul head out to investigate after the crew received a distress beacon from one of the evac pods. They find a body inside the pod with a small creature attached to it. It tries to attack but Liam kills it and it is brought in for inspection. Emily notes that it is part of a long-gone ancient species.
Heading further toward the Roebuck, the Kepler station explodes, sending debris toward the crew. Liam gets hit and suffers a damaged oxygen tank plus fume inhalation, but the others bring him in and help him. They go through the access tunnel to recharge their suits, but Liam’s tank is severely busted. When they keep going, Paul is pulled underwater by one of the creatures before ultimately getting ripped apart while the others are forced to watch.
The remaining four make their way to the Midway station, having to accommodate Liam since his damaged suit will cause him to breathe in more fumes. Lucien attempts to make contact from there, but to no avail. They find the damaged computer systems, and Emily concludes that this is happening due to the drilling work they have been doing. They walk across the ocean floor where they are attacked by another creature. It pulls Liam into a cave, prompting Lucien to help save him by fighting off the creature. While Liam makes it back safely, Lucien and Norah get dragged by the creature. They then begin to ascend, but the rapid increase in pressure threatens both Norah and Lucien, so he willingly sacrifices himself to save Norah.
Norah makes it onto the Shepard station where she finds work from Lucien that indicates he may have known something about the creatures. She also finds a picture of Lucien’s daughter, whom he had been mentioning for a while, revealed to have been dead for some time. Norah then tries to contact Liam and Emily but gets no response. After sitting in despair for a moment, Norah picks herself up, gets a new suit, and continues for Roebuck.
Outside on the ocean floor, Norah finds Emily dragging Liam and goes to help. After succeeding, they finally make it to the Roebuck station. However, there appears to be a whole nest of creatures on the ceiling, and the three must make it inside quietly. They find three evac pods, but the third is heavily damaged and unable to go. After putting Liam inside one of the pods, Norah tries to convince Emily to take the last one. Despite her protests, Norah has to knock Emily into the pod to get her to go.
Just as Emily and Liam’s pods are heading out, the creatures proceed to follow them. Not long after, the large leader monster (Cthulhu) emerges and starts attacking Roebuck. Knowing there is no other way out, Norah raises the energy levels in the station in order to annihilate all the creatures in the ocean. She reflects on her time there and appears to be at peace with her choice, even smiling slightly as the leader and its monsters go down with her.
Before the credits roll, newspaper articles are shown discussing Liam and Emily’s survival, but Tian Industries is doing all they can to silence their testimonies and continue their work in the ocean.
A group of researchers is stationed in an underwater drilling rig. An earthquake forces them to make their way out, but they soon find themselves under attack by creatures that live in the deep. One by one, the crew members get killed.
Engineer Norah Price is among the final survivors. After making it to a nearby station to get to evacuation pods, she sacrifices herself so her other two crewmates can get out since one of the three pods is faulty. The station then comes under attack by the monsters and their leader (Cthulhu). Norah raises the energy levels in the station to destroy the monsters. Although the other two crewmates get out, the company responsible for the drilling plans to continue their work despite the risks.