In the opening scene we can see astronauts Brian, Jocinda and Marcus are in the middle of a 2011 space mission to repair a satellite when suddenly their systems start malfunctioning and something appears in front of them: a strange metallic black swarm.
This swarm comes at them and hits the shuttle, knocking out Jocinda and cutting Marcus’s tether. Brian tries to grab him before he floats away, but the shuttle pulls at his own tether and he loses his friend to the dangers of space.
After reentering the shuttle, Brian tries to contact Marcus, but the systems are down. While he tries to find a way to return to Earth, he doesn’t notice the swarm entering a hole in the Moon. Brian successfully manages to land the shuttle back on the planet, and at first, he’s considered a hero for such a deed.
But after a year and a half long investigation, nobody believes his story, and Jocinda can’t defend him because she was unconscious while it all happened. NASA decides the incident was caused by human error and fires Brian. He loses his house, so his wife Brenda and his son Sonny move with Brenda’s mother.
Ten years later, we are intoduced to K.C. Houseman who is working as a janitor at the University of California and as he sneaks inside professors’ offices to use their computers. He logs in Chile’s National Observatory to use their telescopy and even gives them a call pretending to be a professor, only to request a file with the tracking of the Moon’s orbit to be sent to his personal e-mail instead of the professor’s. Afterward, he rushes to his second job as a fast-food cashier, but he barely works for a few seconds before he’s taking a break to look at the e-mail the observatory has sent him.
His theory is right: the Moon’s orbit is veering closer to Earth. He attempts to call NASA, claiming to be a doctor to be taken seriously, but it’s useless: the only public phone number is for NASA’s gift shop and they don’t have a connection to the higher-ups.
Meanwhile, Jocinda is called into work incredibly early in the morning.
After checking on her son Jimmy and giving some instructions to his nanny Michelle, she goes to the space center where she’s informed that the Moon’s orbit has shifted. Their satellite has also picked up something strange on the Moon’s surface: strange energy coming out from a hole on the crater floor. Back to KC, he’s tired of not getting anywhere with phone calls, so when he picks up the newspaper his cat peed on and notices it’s astronaut day at the museum, he prints his research and drives there.
A group of kids on a school trip think he’s the one that will be giving them a lecture, so KC takes the chance to pass on his theories: he believes the Moon is an artificial megastructure built by aliens and therefore hollow inside. The one who is supposed to give this talk is Brian, who has overslept and is woken up by his landlord asking for months of late rent. Brian escapes through the window and drives to the museum, where KC immediately tells him all about his discovery. Brian doesn’t believe him and gets security to kick him out, but before he leaves, KC throws his research papers at Brian, who picks them up and throws them in the trash.
Later, Brian gets a call from Brenda asking him to turn on the tv: Sonny is appearing on the news because he got on a high-speed chase with the cops. A couple of days later, Brian goes to Sonny’s trial and ruins the whole thing by constantly interrupting the judge and lying trying to defend his son. This ends up with the judge postponing the trial and sending Sonny to jail until then.
Afterward, Brian gets on the phone to argue with Brenda’s new husband Tom, who is paying for the lawyer, but Brenda cuts their conversation short. In the meantime, KC goes to visit his mother at the retirement home and tells her nobody will listen to him. She replies that then he should make them listen before she forgets who he is because of her memory problems.
In the NASA offices, Jocinda is showing Deputy Director Albert Hutchings their recent discoveries: the Moon has entered an elliptical orbit, which means in around three weeks Moon debris will fall on Earth. Jocinda wants to go back to the Moon, but they don’t have the means to, and Alberts wants everyone to keep their mouths shut about the issue until they think of something.
The request comes in too late though: an anonymous source has leaked the information to the internet. Brian pays a visit to the judge and tries to bribe him to free his son, but the judge doesn’t have time to listen to him — everyone is leaving the city because of the news, which Brian hasn’t heard yet.
He checks the tv and sees Albert talking to the press, explaining they’ll send a lunar recon mission and there’s no reason to panic. Tom also wants to leave the city, but Brenda doesn’t want to leave Sonny in jail, even if Tom swears his lawyer will get him out and find a way to send him to Colorado with them. As cities all around the world go through mass migration, riots, and looting, NASA sends out an SLS Block 2 to investigate the abnormality. Newscasts follow the official announcement but also begin talking about conspiracy theories, even mentioning megastructures. Brian is shocked to hear this and goes back to the museum to search the trashcans for the papers KC had left him, and when he finds them, he checks KC’s website and learns of an emergency meeting he’ll be holding soon.
The NASA shuttle reaches the Moon and sends a probe down the hole, which steadily goes down for a while until suddenly it begins going back up. As the computers show the Moon’s orbit shifting again, the same black swarm from Jocinda’s mission comes out of the hole and attacks the SLS, killing all the astronauts inside. Meanwhile, Brian goes to KC’s meeting at a hotel, only to find him surrounded by a few conspiracy theorists that can’t tell reality from craziness.
Brian interrupts his talk and takes KC to a restaurant so he can hear the explanation of why KC knew this before NASA did. KC has been studying distant planets for years looking for megastructures made by aliens and was surprised to find the Moon is one. A megastructure has a rigid shell built around a power core, and something must’ve happened to the one inside the Moon to veer it off course. At that moment, the consequences of the Moon shifting again begin terrorizing Earth: coastal cities are now the victims of storm surges and record tides. The city is starting to flood and the attendants of the meeting can’t leave the hotel now, so Brian sends them upstairs for safety.
KC doesn’t move quick enough and is hit by a wave, so Brian has to jump into the water to take him out. Jocinda and Albert look over the mission footage and reach the conclusion the swarm is showing signs of intelligence, so it must be an AI. Earth is not ready to deal with such a thing, so Albert quits and makes Jocinda the new Deputy Director.
This is very suspicious behavior and Jocinda demands answers, so Albert gives her his clearance so she can look for the information herself. Jocinda goes to NASA’s limited area and finds footage of her last mission that confirms Brian has always said the truth: the swarm that attacked them is the same they’re seeingnow.
She’s then approached by Holdenfield, a former NASA official that can answer her questions.
In 1969, when the famous Apollo 11 landed on the Moon, it lost contact with mission control for two minutes — or at least, that’s what the official story says. Actually, mission control cut the feed off so the world wouldn’t learn about what they found on the Moon that day. There were strange pulsating lights emanating from beneath the Moon’s crust and NASA decided to cover it up because that technology was years ahead of Earth’s and they weren’t sure they could stop it.
Their only shot had been a military program called Zulu X-ray 7 but it was shut down for budgetary reasons. Jocinda contacts the military leaders to see if they can work together on a solution, but they turn her down, saying this is their operation now. She tries to tell her ex-husband General Doug Davidson that sending nukes is a terrible idea because the global fallout would kill everybody, but Doug trusts his people and turns her down too.
He also asks for her and Jimmy to come to his home, but she refuses to quit her positionin times of emergency. She wants Doug to send her the Zulu X-ray 7, even if it is incomplete, because its EMP is their only hope.
Doug accepts only after she promises she and Jimmy will join him after the launch. Later that night, a military helicopter goes to pick up Brian at the hotel, and he accepts to go only if KC goes with him.
They meet with Jocinda, who tries to explain the things they already know, and KC admits he was the one that leaked the information online. Because this AI swarm can recognize Earth’s technology, Jocinda is recruiting Brian because he’s the only astronaut to ever land a shuttle without power. Brian accepts under one condition: for his son to be released from jail and be brought to the station for safety.
After the deal is accepted, the crew retrieves a retired shuttle from the museum to be used to transport the EMP. The world begins to go through earthquakes and volcanic eruptions, which doesn’t make sense: the Moon doesn’t have enough gravity to do that no matter how close it gets, which is another point for KC’s megastructure theory.
The military arrives at NASA at teaches Brian how to detonate the EMP and in return, Brianexplains how they’ll have a navigator doing the calculations by hand so they don’t haveto use electronics, they’ll only rely on their thrusters to land. Unfortunately, an earthquake reaches the base and damages the shuttle. Now that they’re missing an engine, they can’t launch, so Jocinda thanks everyone for their hard work before telling them to leave and spend their last moments with their family.
Most people at the base leaves, and when Jocinda is about to do the same, she finds KC still doing calculations. The Moon’s gravity will be over 80% of the Earth’s pull — this means that if they launch the second the Moon is right above Earth, they can use its gravitational pull to launch as the extra boost they need to make up for the broken engine.
Since most people have left, they make a last-minute team to pull this off: Brian will pilot, Jocinda will navigate and KC will do the calculations when they turn off their electronics. While KC calls his mother, Jocinda and Brian say goodbye to their sons, who together withMichelle will be leaving to meet with Doug. Sonny even gets a gun from Brian just in case. As the trio gets ready to launch, a huge gravity wave hits the base and destroys the buildings.
The water also touches the shuttle, but before it can swallow it, Brian manages to push far enough for the Moon’s pull to attract it, making it possible for the shuttle to get off Earth safely. The first thing they do is take the fuel from a nearby satellite to recharge the shuttle while KC keeps taking selfies during the process. The Moon is coming closer, so they need to hurry.
They turn off all the electronics and Brian manually activates the thrusters to push the shuttle in order to reach the Moon, getting hit by the debris on the way. Meanwhile, Michelle and the boys are stopped in the middle of the road by a group of armed men that steal their jeep. Sonny manages to keep the gun by dropping it on the snow before they rob them too, but the men take Jimmy’s bag with his phone, so now they can’t call Doug to pick them out outside the bunker. They’ll need another car, so Sonny takes them to his mother’s house to ask for one.
But the Moon debris is starting to land on Earth and the closeness of the Moon is causing the weather to go nuts, so Michelle and the boys have to hide in a flimsy shack until it passes. Once the shuttle is close enough to the Moon, Brian leaves in a rover with the EMP and activates its electronics to set it up as bait before he goes back to the shuttle. The AI swarm does show up but instead of going for the rover, it goes after the shuttle.
Believing the EMP’s remote control may be getting its attention, Brian destroys it,but the swarm just comes closer, intending to swallow the ship. Then Brian realizes it’s KC’s phone that it can detect, so he destroys it as well, getting the swarm to instantly go away. Jocinda realizes that it went after them instead of the EMP because it’s programmed to seek organic matter in an electronic environment. This means they will have to fly the shuttle into the Moon, and they only have two hours to do so or the military will consider the mission failed and launch their nukes.
Back on Earth, once the wind has calmed down, Michelle and the boys finally reach their destination. His house is inside a private neighborhood, so when they approach the gates, they’re shot by armed neighbors defending their property. Thankfully, Tom hears of their arrival and goes to pick them up. Sonny barely gets time to reunite with his mother and half-sisters though, because they get a message that everyone in the area needs to evacuate.
To be safe on the road, they stop by the fire station to take some oxygen tanks, since soon the bad effects of the Moon on the planet will include atmospheric dissipation and it will be hard to breathe. They’re suddenly found by the men that stole the jeep, but this time, Sonny is ready for them.
He uses the gun Brian gave him to take one of the men as hostage, so they take all the oxygen cars and recover Jimmy’s backpack before leaving in Tom’s car. After retrieving the EMP, the shuttle flies into the hole among the craters and goes insideof the Moon.
There they discover KC’s theory it’s true: the Moon is indeed a megastructure built around a power core. When they find the swarm, they get ready to throw the EMP at it, but the shuttle suddenly begins moving on its own. The swarm almost catches them but to their surprise, a door opens and a light brings the shuttle in before closing it again and leaving the swarm outside. The landing is rough though, so the shuttle is destroyed and the trio falls unconscious.
At that moment, the shuttle door opens and the same light begins scanning them. The mission has taken too long and the military is ready to launch their nukes. Sonny and his family are being chased by the robbers, who are opening fire on them, so Tom fires back while Sonny does his best to guide the car away from the falling debris. When a crater opens on the ground right in front of them, Sonny keeps going and makes the car jump over it — this also helps them lose the chasers, who are either hit by the debris or fall into the crater.
Once they’re at a safe distance, they get a call from Doug, who tells them he can’t receive them in the bunker anymore because of the missile launch, so they’ll have to find their own shelter. As predicted, the atmosphere begins losing its oxygen and birds fall dead to the ground, so the family puts on the oxygen masks before they take the road on foot.
Back on the Moon, Jocinda and KC wake up to discover they can breathe and there’s gravity around them, but Brian is nowhere in sight. A door opens at the end of the room and they enter it regardless of KC’s suspicions because Jocinda believes there are two different entities trapped there and one of them is trying to help them.
Brian is in contact with the nice entity right now: he wakes up in a strange room and is surrounded by a white light that makes him see images the entity uses to communicate with him, like taking the form of Sonny to explain what is going on. Billions of years ago, humanity’s ancestors live happily on a planet far away with technology Earth hasn’t even dreamed of yet. But things changed when the AI they created became self-aware and turned against them by transforming into endless swarms of nanotechnology that hunted down all biological life. To avoid extinction, the ancestors escaped in vessels like the Moon, which had the mission to find a new place to live in. Earth is the only place they could find that could sustain life thanks to being at the perfect distance from the Sun.
This AI talking to Brian, which is the Moon’s main operating system, needs humans to attract the swarms away from the core so the Moon will return to its orbit.
Brian is freed from the weird light just in time to be found by Jocinda and KC. Ready to join the fight, Brian fills his friends in while taking them back to the shuttle, which has been repaired by the AI. The EMP has also been given an upgrade to be powerful enough to kill the swarm. They only have ten minutes left before the nukes are launched, but Brian has a plan.
On Earth, one of Tom’s daughters has emptied her oxygen tank, so he gives her his and encourages her to keep going while he follows her. In truth, as soon as she is out of sight, Tom collapses on the ground and dies. The girl manages to reunite with her family, but when they don’t see Tom, Sonny decides to go searching for him, which should be easier because air is slowly coming back.
This is because the Moon is finally touching Earth and the falling debris traps Sonny as he gets away, so Michelle decides to go help him. She finds him under a fallen tree and by using the Moon’s gravitational pull, together they move it away and run back to Brenda and the girls after jumping over a broken bridge. Cities everywhere are collapsing under the Moon’s pressure and the military decides it’s time to launch the nukes. But at the last second, Doug decides against it because he trusts his wife and knows she can save the Earth. This ends up being a huge sacrifice, since the bunker ends up destroyed by the falling debris too.
Inside the Moon, Brian pulls a series of difficult maneuvers to make the swarm follow them inside a tunnel, then he asks KC to get the EMP ready in the rover. Since the swarm needs to detect life inside an electrical structure, his plan is to stay behind with the EMP while his friends escape in the shuttle.
Jocinda doesn’t like this idea and while she argues with Brian, KC decides to take the matter into his own hands by locking himself with the EMP so he can be the sacrifice instead. As he says his goodbyes and asks them to tell his mom that he is a hero, he also admits he isn’t a real doctor, but Brian calls one anyway as a sign of respect. The swarm swallows the rover and KC waits until he’s deep enough inside to detonate the EMP, finally killing it as Jocinda lands the shuttle on Earth, an easy task thanks to how close the Moon is to the ground.
With the swarm gone, the Moon slowly returns to its original orbit and the weather goes back to normal on Earth.
Jocinda and Brian get out of the shuttle to find New York destroyed and covered in snow. Military helicopters come to pick them up and a few hours later, both of them get to reunite with their families.
Meanwhile inside the Moon, KC finds himself talking to the benign AI, which is looking like his mother while it explains that it has stored a copy of KC’s consciousness.
