The film begins some years in the future from this exact moment. We see ads everywhere (buildings, walls, bus stops, e.t.c) for the hit game Slayers, and how the star character Kable (Gerard Butler) has four battles left before he earns his freedom. We are then shown a battle in progress: a massive shootout inside a factory. Everyone in the game is controlled by players elsewhere. Characters get points for each kill and for saving a teammate. Some characters are shown to be doing menial tasks in the battlefield, seemingly unaware of all the violence around them. 17-year-old Simon (Logan Lerman) plays/controls Kable and leads him around the factory. After slaughtering most everyone in his way, Kable gets blasted outside of the factory. Kable manages to run to the safe point to win the battle. Afterward, the surviving characters are transported elsewhere. The other characters congratulate Kable on winning, since he now only has three battles left until freedom. Some of the other characters don't believe that anyone will be released from the game.
The producer (Michael Weston) and Chief of Staff (John de Lancie) for the Gina Parker Smith Show discuss their next guest for the show - genius recluse Ken Castle, the creator of Slayers. On the show, Gina (Kyra Sedgwick) talks about the achievements of Ken Castle (Michael C. Hall). He first created a game called Society, which is basically a Sims game but instead of controlling a fake character, the players control a real person and can make them do whatever they want. You can pay to control someone else, or you can get paid to be controlled. Society quickly became extremely popular and profitable, making Castle the richest person in the universe. Nine months ago Castle created Slayers, a controversial game which is supported by the federal government. Castle defends Slayers by stating that each character in the game, though they are real people, are all death row inmates who chose to sign up for the game instead of doing their prison sentence. If a convict can stay alive for thirty battles, they will be set free (though no one has ever survived that long). Some convicts are sent into battlefields with pre-engineered actions to do, and will be set free if they survive just one battle, but are unable to defend themselves (which makes their death rate extremely high). Also, the games are all televised on pay-per-view. Everyone in Slayers and Society has had nano-cells implanted into their brains, which makes it possible for them to be controlled by someone else. They can only be controlled in the perimeter of the game (meaning after the game is over, they get their control back).
After the show is over, the signal is hacked into by Humanz, a resistance group. The Humanz Brother (Ludacris) condemns Castle and states that eventually we will all be his slaves if we continue down this road. Castle gets a kick out of it and has his men try to locate where the signal came from. In prison, a convict beats a guard to death and tries to escape but in the end, he fails. Kable sits by himself and thinks about his family. Freek (John Leguizamo) sits next to Kable. He talks about how Kable spooks everyone else when he sits by himself and is constantly thinking. He can't believe that Kable only has three battles left. Freek asks him why he's in prison. Kable has a quick flashback of a man bleeding in a room. Later on, while sitting in his cell, someone opens the slot of the door and hands Kable a picture of his wife and child. The female voice on the other side knows that his family is the only thing he fights for. She makes Kable sign an autograph and then takes a blood sample from his hand.
Elsewhere, we see Kable's wife Angie (Amber Valletta) going to work as a character in Society. Practically all the game characters are dressed in ridiculous and skimpy costumes. Angie is controlled by an obese man named Gorge (Ramsey Moore). Gorge makes Angie talk to a male character who is wearing a pig nose. The male character licks and gropes Angie while her attention is to a banner across the street for Kable. Suddenly, Society is hacked into by Humanz who continue to condemn Castle. Castle watches a news report about how the hacking shut down the game for a little while and will cost him billions of dollars. Castle shrugs it off, since the money is just chump change to him. Elsewhere, the convicts for Slayers are being transported to the next battlefield. Sandra (Zoe Bell) introduces herself to Kable. The guards don't allow the convicts to talk, and so Sandra is beaten. The convicts run out to the battlefield (a city in ruins) armed with machine guns and bullet proof vests. The game begins and the guns are turned on. A massive shootout ensues with people being blown up, shot to death, set on fire, hit by trucks, etc. Kable sees a female convict pre-engineered to walk in the street as the battle goes on and trucks are driving all over the place. Simon has Kable save the convict from being run over, but she just winds up getting hit by another truck. Sandra saves Kable from being killed, but has her head blown off moments later. Simon has Kable fight through the brutality and win the battle. People all around the world cheer Kable's victory.
During transport, one of the surviving convicts freaks out, wanting to get out. He wonders who exactly is controlling them during the battles. We see that Simon is a spoiled rich kid with the latest technology at his fingertips. Simon makes himself a sandwich and buys an ammo upgrade for Kable with all the points he won from the game. Simon talks with a variety of girls via instant message. A pair of twins flash their breasts to him and offer money in exchange for playing Kable. Simon refuses. His feed is hacked by Humanz, who show Simon footage of Kable shooting a man in the head in a room. A voice tells Simon that if he wants to talk to Kable, they can show him how. Meanwhile, Castle readies to introduce Hackman (Terry Crews) to Slayers. Castle of course has no intention of releasing Kable if he wins two more battles, and so he's purposefully placing Hackman in the game to eliminate Kable. No one will be controlling Hackman, allowing him free reign. A convict, fed up with being controlled, tries to rip the nano-cells form his brain but dies in the process. Freek sees Hackman and tells Kable that he killed a group of people but turned himself in to get in prison. Kable is brought outside for target practice with his upgraded ammo. Kable talks to a guard about being controlled. He doesn't like it, since there's a delay with each control from the player to the character. Later on, Hackman confronts Kable in the locker room with bloody hands. Hackman just killed someone and promises to kill Kable and his family.
For the next battle, Kable suddenly hears Simon talking to him in his head. It's supposed to be impossible for gamers to talk to cons. Simon has fun talking to Kable while the battle ensues. Explosions sound off and motorcyclists race through the battlefield. Kable sees that Freek has been pre-engineered to sweep the ground. Freek winds up being caught in the crossfire and is shot to death. Simon remains desensitized and indifferent towards everyone dying, even though Kable reminds him that they're all real people. Simon has Kable search an abandoned parking garage. Kable exits and wants to go further, but Simon warns him that they're near the perimeter of the game. A rocket is fired at Kable to make him back away from the perimeter. Hackman pops up and attacks Kable. He's about to shoot Kable, but the game runs out of time and the gun shuts down. As the guards take Hackman away, Kable tells Simon that if he wants to win, he needs to turn him loose.
Angie tries to apply to get her daughter back, but the caseworker (Sam Witwer) laughs in her face. With Kable being a convicted murderer and Angie working in Society, he asks if their daughter would really be better off with them. She says yes, but he pretty much denies her application, since the daughter has been relocated to a wealthy family. While Simon buys Kable upgraded armor, his feed is hacked into by Humanz. The Humanz Brother urges Simon to listen to Kable and set him loose. He knows that Castle will not allow Kable to survive. Simon knows that if he were to let Kable control himself, it would be cheating. However, Brother is able to convince Simon to help Kable. In his cell, Kable is approached by the same woman who took his autograph/blood. She tells him that Simon will grant him control of himself, and that he needs to escape his final battle if he ever wants to see his family again. Kable tells the voice that he needs to be drunk.
While suiting up for his final battle, Kable finds a bottle of vodka in his vest. He downs the entire bottle before running outside with the other convicts. Kable, drunk, stumbles around the battlefield while Simon unhappily watches. He tells Kable to pull himself together if he wants to survive. Kable goes to the parking garage and forces himself to vomit in an ethanol gas tank of a truck. He then pisses in the tank and is able to start the truck. Before he can drive away, Hackman hangs onto the side of the truck. Kable beats Hackman and makes him crash into a pillar. Kable is pursued by guards in trucks. He manages to kill them and cause them to crash into each other. Kable crashes through the perimeter and runs from the truck just before a rocket is fired at him, blasting him away. The broadcast of the game stops and everyone assumes that Kable is dead. Gina doesn't believe it though and knows that Kable will try to reach Angie. While Angie is controlled by Gorge in Society, Kable goes to her apartment looking for her. Trace (Alison Lohman), a member of Humanz, approaches Kable and reveals herself to be the woman he talked to in prison. She has Kable get on her motorcycle and they drive off to the Humanz headquarters.
Kable asks why they took a blood sample from him. They used his blood to crack his specific nano-code, which allowed Simon to talk to him (and for the Humanz to eavesdrop into their conversation). They know that Castle is afraid of Kable being free, and so they helped him escape. They want Kable to help them bring Castle down before he makes everyone his slave, but Kable isn't interested. Brother mentions that they know where Angie is. Gina has already located her and follows her in Society. Gorge makes Angie go to a bar where she meets the extremely horny Rick Rape (Milo Ventimiglia), who is a previously banned character. They go to a hotel, where he can't keep his hands off her. When they get to their room, Gorge has Angie bend down so that she can have sex with Rick. Angie clearly doesn't want to do it, but has no choice. Before Rick can violate her, Kable shows up and breaks Rick's back, killing him. Kable orders Gorge to let go of his control, but he can't and continues to talk through Angie. Kable goes to the elevator to leave with her when Hackman shows up. He shoots Kable in the chest, blasting him into the other room where characters are engaged in all kinds of S&M. Hackman takes Angie and gets in the elevator.
Kable, still wearing his body armor, gets up and races downstairs. Two Society characters get in the elevator and make out. Gorge tells Hackman to kill the other characters, which he happily does. Gorge gets off on the violence while Angie is afraid. When the elevator opens, Kable grabs Hackman and fights him. He winds up grabbing a gun and blows off Hackman's foot. Castle's guards show up and engage Kable in a shootout. Kable asks Gorge where to go, and he has Angie lead him to a rave filled with Society characters. The guards follow and get in another shootout with Kable. A couple of Society characters are killed in the crossfire. They run outside, where Gina pulls up in her van. She tells Kable that she'll help him, and so they get in. Meanwhile, Simon is interrogated by Agent Keith (Keith David). Keith tells Simon that the authorities are going through his computer and all his files. He wants Simon to tell him how Kable managed to escape from Slayers.
Gina drives to the Humanz headquarters, where they help Angie. They can't take the nano-cells out of her, since they are fully integrated in her brain. However, they inject her with something that will help stop her from being controlled. Brother tells Kable that Castle first tested the nanotechnology on two military subjects Kable and Scotch (Johnny Whitworth). Some weeks later Scotch was dead, Kable was in prison, and the project was shut down. The same technology was seen again later on when Castle came out with Society. Brother wants to know what happened during the project, since Castle wanted everything associated with it buried. Castle's goons go to Gorge's apartment claiming to be tech support. Meanwhile, the Humanz examine Kable's memories. During the project, Kable entered a room with Scotch. Kable pulled out a gun and aimed it at Scotch. Kable tried to control himself but couldn't. Castle, manipulating Kable, made him kill Scotch. Angie wakes up and reunites with Kable. She tells him that she tried to stop the government from taking their girl but failed. Trace tells them that the Humanz found out that Castle adopted their daughter.
Kable, full of rage, leaves to get his daughter back. Gina runs after him, but he tells her to leave him alone. Gina sees Castle's henchmen arriving and infiltrating the Humanz headquarters. Simon is released from custody after questioning. He goes back home and finds a bombardment of hate mail. Castle knows that Kable will come to him. Kable enters Castle's mansion and sees his daughter sitting in a room. He runs over to her but can't enter the room. It turns out to be a simulation projected on a screen. Castle tells Kable that it's his latest invention. Kable finds Castle controlling several other people and doing an elaborate song/dance number. Kable fights and kills all the henchmen. Kable gets his hands on Castle, but he threatens his daughter. He reveals that he located the Humanz headquarters and slaughtered everyone. He also reveals that he implanted the nano-cells into his own brain years ago. While everyone else is set to receive, his are set to transmit. He can control anyone by thought alone. His plan is to control everyone in the world and make them do whatever he wants.
Castle leads Kable to a basketball court, where Hackman is shooting hoops with his new foot. Castle controls Hackman and makes him attack Kable with a knife. Kable brutally beats him (including breaking his arm) and snaps his neck twice to kill him. Kable grabs the knife and tries to use it on Castle, but he controls Kable to stop. Meanwhile, we see that Trace survived the Humanz slaughter. She and Gina broadcast Kable's nano-code to the world, giving a live feed of what he sees. Castle makes Kable slice his leg with the knife. He then takes off his shirt and beats Kable while the world watches. Castle has his goons bring in Angie and her daughter. Castle controls Kable and tries to have him kill his daughter with the knife. Kable suddenly slams the knife into the floor, picks it up, and tries to use it on Castle. Simon has regained control of Kable's body. As they fight for control over the knife, Castle boasts "I think it, you do it!". Kable tells him to think about getting stabbed in the gut. Since Castle thinks about it, Kable is able to stab Castle and kill him. The world cheers Castle's demise. Kable has Castle's technicians turn off the nano-cells, making them free. The film ends with Kable, Angie, and their daughter driving off into the unknown.