In 2011, astronauts Brian Harper, Jocinda Fowler, and newcomer Marcus are on a Space Shuttle mission to repair a satellite. Suddenly, a mysterious Black Swarm attacks the orbiter, killing Marcus and incapacitating Fowler before Harper can re-enter the shuttle. Although he is initially hailed as a hero for successfully returning the crippled shuttle to Earth, Harper tries to tell his story, which is dismissed by NASA. After an eighteen-month-long investigation, human error is blamed for the incident, and Harper's account remains widely disbelieved. When Fowler fails to defend him during the hearing, Harper is fired from NASA.Ten years later, conspiracy theorist K.C. Houseman, who believes the Moon is an artificial megastructure, secretly uses time on a research telescope and discovers that the orbit of the Moon is now veering closer to Earth. He attempts to share his findings with NASA but is unsuccessful in his efforts. He then turns to Harper, who dismisses him, leading Houseman to go public on social media with his discovery. NASA independently discovers the anomaly and mounts a Moon mission using an SLS Block 2 spacecraft to investigate the abnormality. The same alien Swarm that attacked Harper's shuttle a decade earlier reappears, killing all three lunar astronauts after they drop a probe into a kilometers-deep artificial shaft that has opened up on the Moon's surface.As the lunar orbit continues to deteriorate, the Moon falls closer and closer to Earth, causing cataclysmic disasters such as tsunamis, gravitational abnormalities, and atmospheric dissipation. Fowler, now the deputy director of NASA, learns that Apollo 11 had discovered lunar surface abnormalities during its historic landing and that a two-minute radio blackout was meant to conceal how the Moon resonated strongly when the spacecraft's fuel tanks were jettisoned, hitting the lunar surface, suggesting that it had a hollow interior. A military program code-named ZX7 had created an EMP device in an attempt to kill the Swarm but was abandoned for budgetary reasons. Fowler orders the EMP device brought out of storage and brings the retired Space Shuttle Endeavour out of its museum to serve the new mission. Harper, Houseman, and Fowler launch with the EMP, narrowly escaping to orbit as a gigantic tsunami wave destroys Vandenberg Space Force Base.As the crew enters the interior of the Moon, they discover that the Swarm is siphoning off energy generated by a white dwarf located at the center of the Moon, causing the artificial megastructure's orbit to destabilize as its power source is depleted. Harper learns that the megastructure was constructed by the ancient ancestors of humanity, who were more technologically advanced than their present-day descendants. The Moon was constructed billions of years in the past as a space ark to repopulate humanity, which was being hunted by a rogue artificial intelligence that grew too strong. The Swarm on the Moon is one of those malicious AIs, which responds to electronic activity in the presence of any organic life. As the Moon continues to approach the Earth, the President of the United States gives the Chairman of the Joint Chiefs of Staff, General Jenkins, orders to launch a nuclear strike at the Moon. However, the Air Force Chief of Staff, General Doug Davidson, refuses to carry out the strike order, so he can save the lives of his ex-wife Fowler, as well as both Harper and Houseman while sacrificing his own life in the process.Meanwhile, Harper's son, Sonny, escorts Fowler's son, Jimmy, and their nanny, Michelle, in an attempt to reach Davidson's military bunker in the Colorado mountains. They reach Aspen and reunite with Harper's ex-wife and Sonny's mom, Brenda, as well as his step-family. But they are caught in the multiple disasters caused by the rapid destruction wrought by the near proximity of the Moon. As the group makes their way towards the bunker, they fight off other survivors and increasingly deadly natural disasters before reaching the safety of a deep mountain tunnel. Brenda's husband, Tom, sacrifices himself to save his youngest daughter, suffocating as the Moon strips away the localized atmosphere by its gravitational pull during a close by orbital pass.Houseman uses the EMP device and their lunar module to lure the Swarm away from their spacecraft before detonating the device. His sacrifice obliterates the Swarm and allows Fowler and Harper to escape to the now nearby Earth. With its power and systems restored, the Moon structure begins to return to its regular orbit. Fowler and Harper successfully land their spacecraft in Colorado and are eventually reunited with Sonny, Jimmy, Michelle, and Brenda.The Moon's operating system, itself an AI being created by humanity's ancient ancestors, reveals that it stored a copy of Houseman's consciousness as he sacrificed himself. Appearing to the reconstructed Houseman as his mother and cat, Fuzz Aldrin, the AI projection remarks that they now need to get to work on repairing the massive destruction wrought upon the Earth.