In the year 2154, the earth is polluted, vastly overpopulated, and disease runs rampant through the dilapidated slums that the cities have become. The wealthiest people have fled the planet and taken refuge on Elysium, a Stanford Torus high-tech space station, just beyond earth's atmosphere.
While those on Earth are policed by ruthless robots, Elysium's citizens are governed by President Patel (Faran Tahir), in a utopian setting which includes access to private medical machines, called "Med-Bays," that offer instant cures for virtually any disease or ailment a person may experience.
A young boy named Max DeCosta (Perry Cotton) his young girlfriend, Frey Santiago (Valentina Giros), are living in the ruins of Los Angeles. Frey can read and she reads Max stories about Elysium. Max lives in an orphanage with a kindly nun. The nun says he is born to do something great.
Frey and Max are looking up at Elysium, which is visible from earth. Max intends to go there someday and promises to take Frey with him. Frey takes a pen and marks on Max's hand. She inscribes a circle and the letters M + F.
Years later, when he's 36 years old, Max (Matt Damon), sports numerous tattoos and wears an electronic ankle bracelet. He is preparing to board a bus to travel to his job. Two security robots approach him as he's standing in line. They rip off his backpack, then hit him twice, breaking his wrist. He's a felon, a former car thief, and on parole, so he's frequently singled out for harassment.
Matt, identified as #6722, and Frey, now a nurse, accidentally meet at the clinic where he goes to have his a arm treated. Matt asks her to have coffee with him, but she declines. Finally, she agrees to meet him soon.
Matt had been ordered by the robots to go see his parole officer, another robot. The parole officer robot can detect "attitude" and it doesn't like Matt's, so his parole is extended. The robot then offers Max a pill to help calm his heart rate, which it has detected as elevated.
Max works at an assembly line for Armadyne Corp, a company which supplies Elysian weaponry, as well as the robots which police the Earth. The shift supervisor docks him half a day's pay for being late.
Partaking of an illegal emigration operation, some of the people in Los Angeles were able to come up with some money which they use to acquire Elysium identification brands on their wrists, then they board three dilapidated looking shuttles, which take off and flies towards Elysium. The shuttles require codes, which were also stolen.
A French-speaking woman named Delacourt (Jodie Foster) is the Defense Secretary for Elysium. When she's told about three unauthorized shuttles approaching, she overrides Executive Order 355 and activates a rogue sleeper agent named C.M. Kruger (Sharlto Copley). Kruger immediately grabs a shoulder-fired ground to air missile launcher and fires off four rockets. The rockets chase down the shuttles and destroy two of them, killing all 46 people on board. The other shuttle makes it to Elysium and lands. The rich folks in the area are all in a tizzy, as helicopters and robots give chase of the occupants of the shuttle.
One mother and her daughter who were on the shuttle that landed rush into a house and find a Med-Bed. The girl's wrist is scanned and she is identified as an Elysium citizen. A machine then assesses her physical condition, determining she had multiple fractures, and begins repairing the broken bones.
There end up being 32 arrests and 13 casualties, with two at-large. The at large were the mother and daughter, who are soon apprehended. All 34 are prepared for deportation back to earth.
Matt's friend Julio (Diego Luna), tries to entice him to come back into the auto theft game, but he refuses, wanting to complete his parole and find a way to get up to Elysium.
At Matt's work station, a pallet jams open the door to the firing unit for the robots. The supervisor orders Matt to un-jam the door or he will lose his job. Matt has no choice but to squeeze into the chamber and push the pallet away from the door. When he does that, the door slams shut and the radiation powers on. Matt receives a lethal dose of radiation. He is told he will die in five days.
Armadyne CEO John Carlyle (William Fichtner) goes down on the production floor to see what the emergency was. He sees Matt lying on a bed in the infirmary and orders that Matt be taken away so he won't mess up the bedding. A robot gives Matt some pills to help him deal with the inevitable discomfort.
President Patel summons Delacourt. She is brought before the President and his cabinet. They are not happy with her for ordering the shuttles shot down, and for using Kruger to do it. Delacourt is impudent, as she sasses Patel and all but calls him a coward who would see Elysium destroyed if not for people like her. Patel threatens to fire Delacourt if she screws up again. He orders her to stop using Kruger.
When Kruger learns that he's not going to be utilized anymore, he's angry and feels betrayed.
Julio sees Max returning from the infirmary, barely able to walk, and rushes to help him. Julio helps him take some of the pills. Max tells Julio that he wants to go see Spider (Wagner Moura), the rebel behind the illegal transports to Elysium, about getting to Elysium. Max is desperate to make the trip now, as he needs a Med-Bay to heal himself.
Frey has a young daughter, Matilda (Emma Tremblay), who experiences seizures. She had been taking her to work with her, but was ordered to leave her daughter home, as the doctors weren't able to give her treatments.
Max and Julio got to the high tech rebel command center where Max asks Spider for an identification brand and a ticket to Elysium, promising to come back and work for him. He reminds Spider that he did three years in prison for him. Spider decides to make Max an offer. If he'll plug into the brain of one of Elysium's high-ranking officials and obtain pass codes and other secret data that would provide Spider access to money, then he'd make sure Max was able to get to Elysium.
Max must submit to surgery by what appear to be nothing more than glorified tattoo artists. They surgically attach a third generation powered exoskeleton to Max's body and insert a data collection device in his brain. The exoskeleton gives Max the strength of a droid.
Max tells Spider that his friend, Julio, had to be included in the deal, and that John Carlyle must be the high level target.
Delacourt, vowing to protect Elysium and her own power, bargains with Carlyle to create a program that can override Elysium's computer core to give her the Presidency. Carlyle would be beneficiary of a 200 year contract to provide essential services to the community of Elysium. Carlyle works up a new computer protocol called "Sabre Cerebral Defense," and programs it into his own brain device. He also encrypts it with a denial system that would prove lethal to anyone attempting to download and use the program. He then boards a shuttle for a flight to Elysium.
Max, Julio (Diego Luna) and a team of Spider's men arm themselves and make use of two fast armored vehicles. They are aware of Carlyle's planned flight to Elysium and they set out to intercept him.
Max shoots an explosive device at the shuttle. It attaches itself to the side of the shuttle. As there is only 15 seconds until the shuttle goes supersonic, the explosive device must be detonated in short order. Once the shuttle has cleared it's launch facility and has traveled a short distance, the explosive is detonated and the shuttle is forced to crash land.
Delacourt calls Kruger as soon as she's informed that Carlyle's shuttle has gone down, and that a former felon named Max De Costa was responsible. Kruger demands that he be "re-instated" if he decides to go rescue Carlyle. Delacourt says ok, then arranges for two of Kruger's former associates to go pick him up.
Max and his men arrive at Carlyle's shuttle and are confronted by one of two droids who were on the shuttle with Carlyle. After a difficult fight, Max destroys the droid. One of the men then uses a device to cut through the hull of Carlyle's shuttle and provide access to him. However, the second droid exits on the opposite side and comes around to confront Max and the others.
Max and the others exchange fire with the droid. One of the men is firing his weapon while keeping his body hidden, so he can't see where his rounds are going. Max warns him not to hit Carlyle, but that's just what happens. Carlyle is shot in the chest. Max then engages the droid in hand-to-hand battle and ends up ripping the droid's head off.
Max and his men quickly establish a head to head computer connection between Max and Carlyle, but something is wrong and Max's computer expert says he can't read the data being transferred. They are out of time, as Kruger and his cohorts have arrived. When Max tries to run, he collapses and Julio has to pause to help him. Kruger's weapons on the shuttle he's in are very effective. He shoots and flips over one of the vehicles Max and his men had been using.
Kruger lands his shuttle and gets out and attacks Max, stabbing him. Kruger is about to decapitate Max when Julio shoots Kruger in the neck. Kruger then runs his sword through Julio. Max recovers and shoots at Kruger, but Kruger's own droid outfit has a force field that shields him from it's effects.
Delacourt ordered that Max be captured but that his brain be left undamaged.
Carlyle dies and Max is able to escape. As he stumbles along, with Kruger and his men in pursuit in the shuttle with sophisticated tracking equipment, an old lady hides Max under her cart filled with pigs, thus helping him evade detection.
Kruger deploys six tracking discs that start flying around the city attempting to locate Max. Delacourt issues a "No Fly" order for all craft in the Los Angeles area, so that Kruger can search unimpeded. Kruger now knows what the data transfer between Carlyle and Max was all about.
Max goes to see Frey, calling out to her on the street as she was leaving her job. He begs her for help, telling her she couldn't tell anyone. She takes him to her home where she has the necessary medical supplies to help him. As she's tending to his stab wound, she notices a tattoo he has, a circle and the letters F + M. That was the same thing she once wrote on his hand with an ink pen when they were children.
Max is saved by Frey and he meets Matilda. Frey tells Max that Matilda has leukemia. She asks Max to find a way to get Matilda to Elysium, so she can be cured. Max tells her it's too dangerous, and he can't do it.
Matilda tells Max a story about a meerkat who is hungry, so he befriends a lonely hippo in order to get some fruit. The point of the story was to indicate how creatures in need can find ways to help one another. Max just says he's sorry and then he leaves.
One of the search discs finds Max once he's back out on the streets. Max throws a rock at it and knocks it out of the sky, but not before Kruger has seen Max. Kruger and his men quickly travel to Frey's place and bust in, demanding to know where Max is. They take Frey and Matilda with them in the shuttle.
Max goes to see Spider and demands he fly him to Elysium immediately. Spider tells Max that there's a no-fly order in effect and it can't be done. Spider then connects to the port in Max's head to see what data had transferred from Carlyle's head. He quickly realizes it's a reboot program for Elysium, something of tremendous significance.
Max realizes he can trade the data for his cure and decides to leave. Spider has to quickly order his men not to shoot Max. Max is desperate to get to Elysium so he can heal himself of his radiation poisoning.
Max returns to the site of the disc he'd knocked out of the sky and he looks into its camera and tells Kruger to come get him. When Kruger arrives, Max produces a grenade and pulls the pin, telling Kruger that if he doesn't take him to Elysium, he will blow his own head off and destroy the reboot program. Kruger invites Max on board the shuttle, where Max is surprised to see Frey and Matilda. They start the 19 minute trip to Elysium.
Delacourt lifts the no fly restriction on L.A. Spider knows that Max is on a shuttle and bound for Elysium, as he'd attached a tracking device to Max before he'd taken off. Spider and two of his men get on their own shuttle and take off for Elysium.
Kruger sings softly to Matilda and kisses Frey on the forehead. He's feeling an attraction for Frey and is willing to help Matilda as a result. When one of Kruger's associates approaches Frey, Max tells the guy to back up. Kruger then lunges and grabs at the grenade in Max's hand. They struggle. Max and Kruger fall and the grenade rolls free. It blows up and removes half of Kruger's face. The shuttle also becomes uncontrollable and crash lands on Elysium.
Max carries Matilda to a safe spot away from the shuttle, then opens the shuttle doors and goes back for Frey, who was trapped in her seat. He frees her and she goes and gets Matilda and carries her into a mansion as Elysium security forces are arriving. Max, meanwhile, has to fight with one of the bad guys on the shuttle. The second bad guy takes off after the girls.
Frey places Matilda in a healing bed inside the mansion, but because Matilda isn't recognized as a legitimate citizen, the bed won't work. Kruger's goon arrives and tasers Frey. Max ends up getting tasered as well.
Delacourt, who has told President Battelle that because the intruders have committed an act of war and that she was now in charge, wants the data extracted from Max's head, which her expert tells her will kill Max. She's fine with that.
Spider arrives in his clanky old shuttle, managing to land without incident. He immediately heads for where his tracking device indicates Max is.
Kruger's goons take Frey and Matilda away. They put Kruger in a machine which completely reconstructs his face and head in about 30 seconds. He then wakes up. He survived only because his brain had not been damaged by the grenade explosion.
Max breaks loose from his bonds and disables the two lab techs who'd been working on him. He forces one of them to tell him where Frey and Matilda had been taken.
Delacourt approaches Kruger, who's still feeling out of sorts and very much on edge. When she starts criticizing him for stupidly crashing the shuttle in a suburban area, he angrily smashes the mirror he'd been examining his face in. He picks up a fairly large piece and jams it into the throat of Delacourt. She goes down, bleeding badly.
Kruger makes it clear that he intends to use the data deposited in Max's head to re-program Elysium and make himself the new president. Kruger tosses Delacourt into the room with Frey and Matilda. Kruger tells Frey that he was going to make sure her daughter was never healed. Kruger's goons start roaming around tossing grenades to take out Elysium's command and control structure. Matilda starts treating Delacourt's wound, but Delacourt stops her, preferring instead to die.
Max calls Spider and they make their immediate plans. Max then heads for the armory and takes the last of his pain pills.
Kruger is now outfitted in a military-grade exoskeleton far superior to Max's droid suit, then orders his goon to kill Frey and Matilda. The goon plans to have some fun with Frey first, but Max gets there first and he is of superhuman strength after taking those pills and he just crushes the goon, slamming him against the floor. The second goon comes in shooting and Max grabs an automatic weapon and just shreds the guy.
Max sends Frey to the surface with Matilda, telling Frey to get Matilda to a Med Bay, promising her that it will work this time. Max teams up with Spider, reminding Spider that they have a deal only if Frey gets her daughter to a Med Bay. Spider sends one of his men to help Frey.
Kruger blows up one of Spider's men. Some high frequency sounds are broadcast, which disables Max, as he can't bear them. Kruger then goes after Max with his sword. In a desperate fight on a high catwalk, Spider tackles Kruger before he can stab Max and Kruger's sword goes flying several levels below. Kruger then jams a knife into Spider's hand, taking him out of the fight.
Max and Kruger engage in hand-to-hand combat. Max is losing the fight, when he suddenly executes a body flip and disengages Kruger's exoskeleton power source on the way down. Kruger manages to clip Max to a railing and then pulls the pin on a grenade, intending to blow them both up. Max pulls himself loose and flips both Kruger and the grenade over the railing. Kruger explodes in mid-air.
Spider makes a cable connection to the port in Max's head at the same instant that Frey flips the switch on a Med Bay containing Matilda. Spider first confirms that Max wants him to proceed, as the data download process will be fatal to Max. Max confirms, but first he connects to Frey and tells her goodbye. Max then presses "Enter" on Spider's computer, just as President Patel arrives with security to arrest Spider. The Elysium reboot takes place and everyone on earth become citizens of Elysium. Max dies, Spider is released, Matilda is healed, and numerous Aid shuttles are sent to earth to help the new citizens.