ERIC COLEMAN joins a crew headed for the bottom of the Pacific Ocean to leave his life on the shore. A widower, Eric finds a position as a turbine energy specialist aboard The Thales, a renewable energy station off the coast of Northern California that will capture the power of the Pacific’s current, providing clean power to an economically crumbling west coast.
Alongside single mother and nurse, STACEY KERN, the two endure a pitch-black descent into the dark abyss. They join the rest of the crew on The Thales, a station that looks like a sunken space shuttle. The pipe and cable ridden cavern is surrounded by massive kite fields, that house thousands of turbines spread out across the ocean floor. The crew prepares to power up the station and transmit much needed clean energy to the western coast of the United States.
JOHN DOWNING, one of the bearded brothers who drive the submersibles, knocks a turbine loose during routine procedure, slamming the large encased technology into The Thales. A pressure valve ruptures. It does its job in containing the flooding, but IAN LOWE, the managing director of operations, brings Eric to the flood room along with his two engineers, CAMERON WEBB and CODY SEACREST, to seal the breach. All four men are injured, but they stop the rupture and The Thales is saved from destruction.
Power and communications go down during the emergency. Their technical director, DEVIN FLANNERY, and corporate liaison, KARINA TROWBRIDGE, work tirelessly to restore functionality. Stacey did all that she could but the four injured men need to be taken to the surface and a hospital. Cody fights through a concussion to get power back on in The Thales. However, doing so led him to a dire discovery, someone had tampered with the system during the pressure valve breach. One of the crew meant for The Thales to fail. Another pipe bursts, burning Stacey and leaving over half the crew injured, needing extraction.
As they wait for rescue, Ian panics. A former Captain in the Navy, his lack of action caused the untimely death of two Seamen under his command. His past trauma causes paranoid resorting to primitive methods. He has the crew celebrate as a distraction, until he can find the right way to uncover the identity of the saboteur. After the celebration, he lures Cody, Eric, Devin, and DAVID DOWNING, the second submersible driver and younger brother, into the engine room. There, he tortures them to find out who was responsible. The rest of the crew attempts to break into the locked room.
Karina, in an act to get him to stop hurting the innocent, reveals herself to be the saboteur. She was promised her old job back on the executive team, if she helped to incapacitate The Thales. The energy company served to gain lucrative gains in their oil investments from the disaster and their sizable insurance would help rebuild The Thales. She never meant for anyone to be harmed.
As the crew prepares to leave for the surface, Devin attempts to contact the shore to let them know the sabotage didn’t work. He was also involved but said nothing in the engine room, leaving Karina to be the sole guilty member. He runs through a reboot to get The Thales to operational level. The shore station overrides his command, and opens every available hatch to flood the entire station.
Amidst the incoming flooding, the crew is split into four groups. Devin, Stacey, and David enter The Archimedes, one of two submersibles. Water starts entering the submersible, and they have no choice but to leave the rest of the crew behind and start their ascent. John pulls a severely injured Cameron into the other submersible, The Anaximander. He doesn’t shut the door on time and they are flooded. With water up to their necks, the submersible cannot ascend properly. The submersible falls against a turbine, launching the emergency buoys meant to inflate and bring them to the surface. Instead, the submersible catches on the turbine, leaving them tethered to the ocean floor without power. Karina and Cody are pushed into the flood room. Karina’s back is crushed under scaffolding as it is torn apart by the Pacific. Cody carries a paralyzed Karina to the top level, only to find they have nowhere to go. The station is flooded. They tie themselves to one another to avoid floating about in the station, and wait for the water to take them. The two embrace one another in an attempt to find peace as they are consumed by the Pacific Ocean. Eric is shoved back by the incoming water into the recreation room; Ian follows him in to save him. He’s too late and they cannot get out. He seals the room in a moment of desperation, leaving them both stuck inside a small room with no power and no way out, the Pacific Ocean entombing them.
Communications are down in The Archimedes, and in the process David discovers Flannery was a part of the sabotage as well. They rely on a basic CB radio and hope an old fisherman they met on the docks is in his favorite spot, their only real chance at rescue. As they ascend, the light seems particularly absent. A storm rages above the surface and they enter it with a submersible, a device meant to navigate underwater, never travel on the surface. They are tossed upside down and the old fisherman saves them by “fishing for humans.” The fisherman reveals that federal agents have overtaken The Boundless, the rescue ship that was nowhere close to reaching them. The fisherman takes them to The Boundless.
John struggles to keep Cameron conscious. He’s losing blood and with their bodies underwater, he can’t close the wound or even keep a bandage adhered. As oxygen runs low, John pulls out a scuba tank. Cameron refuses, knowing he is moments from death. John fights the notion. Still Cameron dies, leaving John with no knowing whether rescue is close, or even coming. He prays his little brother made it and isn’t far away.
Eric and Ian are at odds. Eric wanted Ian to leave him behind and save himself. Ian cannot understand why. Eric reveals that the reason his wife died was because he confronted his wife’s stalker, an ex-boyfriend. He responded to the stalker’s threats, giving him enough information to find her. Eric believes he should die for what he did and the flooding was his chance to join his wife in the afterlife. Ian pleads with him to not throw away the life he was given, revealing that he’s made a series of terrible decisions that alienated Ian from his family. He hasn’t even met his granddaughter because they won’t allow him near any of his family. He believes saving Eric could be his last chance at salvation and reconciliation.
They make their way through the air duct system, reaching the control room where they are able to send a distress signal. The pump systems cannot keep up with the power of the Pacific. Until they can find a way out of the station, any rescue effort is meaningless.
David, Stacey, and Flannery board The Boundless, where they meet federal agents who investigated the energy company for years. They formulate a plan to retrieve Eric, Ian, and John. Flannery gives a drive to the lead federal agent with files revealing how the sabotage cam together. David insists that he drive one of the submersibles on the rescue, and demands that Stacey drive the other. They’d spent time teaching and learning, respectively, as they prepared the station and worked on The Thales. They begin their descent, untethering John from the turbine.
With a plan to seal The Thales, Eric and Ian still have to figure out how to purge the Pacific from the station. Eric recalls the formula for the turbine energy consumption. It was based on calculations for wind. He reconfigures the yaw motor, causing the power emulsion to increase three-fold. Their avenue of escape will arrive just as the structural integrity starts to give.
David welds a panel over a breach to seal The Thales. The shore station restores power to The Thales’ backup generator, closing open hatches and firing up the flood pumps to push water from the station. It will give Eric and Ian time to get to the submersible Stacey is driving, with Flannery accompanying her in an act of contrition. The welded panel cannot take the pressure, and they have to force Eric and Ian to evacuate before they’re ready.
Ian opens the door, letting the ocean in and forcing Eric to decide if he’s ready to live, as his late wife would have wanted. Ian is knocked back and injured. Eric swims to save him and they make their way. The welded panel could give at any moment. They reach the submersible just as the panel gives away. The water slams the access door to the submersible shut, closing on top of Flannery’s skull. He lands lifeless on the submersible floor. Stacey starts the ascent and does what she can to help.
MATTHEW MCCREARY, a senator who spearheaded the stimulus package to build The Thales is called in for an emergency summit. Federal agents hand him a copy of Flannery’s drive, and McCreary understands the men and women he worked with both in Washington, and at Maritimus Energy, built an elaborate sabotage that resulted in the death of innocent people. Flannery succumbs to his injuries, resulting in four deaths of the nine crewmembers. McCreary makes a public statement, revealing the elaborate plan for financial gain.
Ian is arraigned on charges of assault for torturing the crew. He meets up with Eric one last time before heading in, thanking him for saving him in every way imaginable. Eric flies back home to find a package from Ian. In it is a letter and a picture of the time when Ian was able to meet his granddaughter. The letter explains formula proved that The Thales ad the capacity to power the entirety of North America, he had found the means to power the world. A second picture is of Eric’s late wife. Ian tells him “Always remember, my son, your true love never leaves you.”