A guy relies on his newly-acquired gladiator skills to save his ex-girlfriend from kidnappers.
Miles Harris is an ordinary computer programmer who gets thrown into an underground criminal fight club called Skizm, where players must kill each other for the entertainment of others. He has guns bolted to his hands and is pitted against star player Nix.
Skizm’s leader Riktor ups the stakes by kidnapping Miles’s ex-girlfriend Nova. Miles is found by detectives, one of whom is Nix’s father who lost his wife and son after Riktor sought revenge on him for putting him in jail. Miles and Nix team up to take Skizm down together.
Miles and Nix kill Riktor’s henchmen, with Nix sacrificing herself with explosives to take every last one of them out. Miles finds Riktor on the roof trying to get away with Nova, but even as Riktor shoots him, he manages to pistol-whip him and throw him over the roof to his death. Although Miles is victorious, Nova is horrified that he has become a killer, and they don’t get back together.
After Miles gets his guns taken off, Nova creates a comic book about Miles, “Guns Akimbo”. He now dedicates himself to taking down Skizm’s other locations across the globe.
In an alternate near future, an underground fight club and a criminal organization known as Skizm achieved massive popularity by live-streaming real death matches between criminals and psychos. Ordinary computer programmer Miles Lee Harris, who gets his kicks by trolling online trolls, logs into Skizm’s forum to insult viewers who turn murder into entertainment. Riktor, the criminal kingpin and psychopath who runs Skizm, breaks into Miles’ apartment with his henchmen Dane, Effie, and Fuckface. After being beaten and drugged, Miles wakes up to find guns bloodily bolted into both of his hands. Miles learns that he has been forced to participate in Skizm by being pitted against Nix, the game’s deadliest and craziest killer; she wants out but not after her last opponent, Miles.
Nix tracks down Miles, who tries to explain his unwanted predicament, but Nix merely shoots up his apartment; Miles escapes outside. After unsuccessfully attempting to recruit help from the police, Miles made it to the park for a rendezvous with his artist ex-girlfriend Nova Alexander, who tells Miles she doesn’t want to get back together. When Miles reveals what is happening to him, Nova flees in fright. Nova reports the situation to Detective Degraves. Degraves has his partner Stanton hack Nova’s phone so they can track Miles. Miles gets temporary help from a vagrant named Glenjamin. Miles then goes to the office where he works so his friend Hadley can hack the Skizm tracking malware on his phone.
Miles finally gets assertive by angrily pulling his guns after his continually condescending boss Zander insults him. Nix then suddenly guns down Zander and starts shooting up the office. Miles escapes in a stolen car and Nix chases him on a motorcycle. Following a face-off where he again fails to reason with Nix, Miles calls Nova but sees Riktor kidnapping her. Miles calls 911 and leaves his phone in a junkyard to summon the police. He then inadvertently interrupts a drug deal between two rival gangs. Nix shows up and starts gunning down thugs while trying to get to Miles.
The cops arrive and arrest Miles. While transporting him, Degraves and Stanton explain their plan to use Miles as bait to lure Nix, whom they’ve been trying to capture for years. Degraves reveals Nix is his daughter. Nix was driven criminally insane after Riktor took revenge on Degraves for taking down Riktor’s gang by blowing up his family’s van. Degraves managed to save Nix, but his wife and son died. Stanton reveals he is a mole working for Riktor when he shoots Degraves in the head. Stanton plays a video message in which Riktor explains that Miles has 30 minutes to kill Nix or else he will kill Nova. Miles recovers his phone from Degraves’ body. While coercing a gaming café patron into hacking Nova’s phone to retrieve her location, Miles learns the Skizm communities dubbed him ‘Guns Akimbo’ as he has become the most popular player ever. Miles arrives at Nova’s supposed location to find Riktor waiting. Riktor taunts Miles by dumping Hadley’s dead body before driving away.
Miles manages to secretly meet with Nix and tells her that Riktor murdered her father and kidnapped his ex-girlfriend. In her rage and desire for revenge, Nix agrees to a plan where they successfully stage a scene for Skizm’s broadcast camera drones. She seemingly guns down Miles, who is actually wearing a bulletproof vest he removed from Degraves. Henchmen recover Miles’ body and transport him to Riktor’s Skizm hideout. Nix joins Miles as they take down Riktor’s henchmen, including Dane and Effie. Nix sacrifices herself by detonating a suicide vest that blows up Fuckface and the rest of Riktor’s men so Miles can survive. Riktor executes Stanton while making his way to the rooftop with Nova.
At the rooftop, Riktor keeps shooting Miles, but the latter determinedly charges at Riktor and ultimately throws him off the roof to his death, not before Riktor tells Miles that Skizm has spread worldwide and is becoming a global franchise. After Riktor dies, Miles starts to collapse from massive blood loss while imagining a romantic reunion with Nova. However, Nova actually becomes frightened and goes into shock after seeing what Miles is turning into.
Some time later, Miles is scarred from his injuries and while sitting in his car, he opens a file. He discovers a comic book written by Nova and learns that she is promoting Miles as a popular hero by writing a comic book based on their story. With Skizm spreading worldwide under new leaderships, Miles commits himself to do everything in his power to destroy the entire criminal organization.
The film opens with a virtual floating head criticizing society for enjoying stories, videos, and news articles on subjects like murder and chaos because it distracts them from their own miserable lives. The answer to this is Skizm, an underground fight club where people are pitted against one another to the death while viewers all across the country watch for entertainment. The top player is Nix (Samara Weaving), who is frequently tasked with going against other challengers, but she always manages to brutally kill all of them.
We meet Miles Lee Harris (Daniel Radcliffe), a mild-mannered computer programmer who keeps to himself. He works a dull job for an obnoxious jerk named Zander (Richard Knowles), and spends his free time trolling the Skizm message boards. To his dismay, a Skizm admin manages to track his IP address, forcing Miles to shut off his laptop. He then gets a message from his ex-girlfriend Nova Alexander (Natasha Liu Bordizzo), whose picture he accidentally liked earlier. He dreams about being in a park with Nova where she draws a tattoo on his arm.
Miles gets a rude awakening from Skizm’s CEO Riktor (Ned Dennehy) and his goons Dane (Mark Rowley), Effie (Racheal Ofori), and Fuckface (Set Sjostrand). They smash his laptop and then tranquilize him. When Miles wakes up, he finds that he has guns bolted to both of his hands. He freaks out and gets a message informing him that he has to kill Nix within 24 hours. Nix also gets a message notifying her to go after Miles, stating that this will be her last job before she is free from Skizm, just after she completes a drug-fueled job by massacring a number of goons. She then goes into a police station to track Miles’s phone. She finds his apartment and attempts to kill him there, but he manages to make an escape.
Miles goes out into the street while trying to obscure the guns. He goes to two cops for help, but naturally, they draw their guns on him when they see him hold them up. Skizm drones capture the scene as viewers tune in to make fun of Miles. He is forced to run and hide in an alley. He accidentally shoots a cop but helps cover up his wound before running away.
Miles manages to meet Nova in the park before Nix can find him. When he tries to explain himself, he shows her the guns, leading her to freak out and pepper spray him before running out of her car. Miles ends up in an alley again and just decides to blow his brains out until a homeless man named Glenjamin (Rhys Darby) stops him…because the angle is off and he would just blow his face off. Glenjamin helps Miles dress himself and gives him a dirty hot dog as food before he goes to continue looking for help.
Nova ends up at a police station where she talks to Detective Degraves (Grant Bowler). After she leaves, Degraves and his partner Stanton (Edwin Wright) hack into Nova’s phone to track Miles, but their main target is Nix.
Miles goes to his job to get help from his coworker Hadley (Milo Cawthorne) to remove the tracker from is phone. Zander then comes to chew Miles out again until he finally loses it and draws his guns on Zander to tell him to stop being a dick. Before Zander can turn over a new leaf, Nix shows up and puts a bullet in his head. She shoots at Miles, who escapes by stealing a car. She chases after him on a motorcycle and catches him in an abandoned building. Miles tries to reason with Nix, but she continues to try and kill him. He shoots at something that explodes, which briefly distracts Nix as it triggers her PTSD.
Miles calls Nova as he tries to explain himself again, but Riktor and his goons break in and kidnap her. They order Miles to kill Nix, or they will kill Nova. As he runs off, he stumbles into a drug drop, and all the guys involved try to kill him until Nix shows up and pumps everyone full of lead. Miles accidentally shoots one of the main dealers in the neck, where he slowly and painfully dies, and it clearly messes him up.
Degraves and Stanton find Miles and arrest him. He thinks they will take him to the hospital, but Degraves says they need him to get Nix to go to them. He reveals that he once put Riktor behind bars, but when he got out, he targeted Degraves’s family with a car bomb. He pulled his daughter out but lost his wife and son. His daughter is Nix, and she grew up to be insane as she targeted Riktor and got caught up in Skizm. Stanton then shoots Degraves in the head and shows Miles a video message from Riktor stating that he has a half hour to kill Nix, or Nova dies.
Miles goes to a gamer cafe and gets one of the ladies there to help hack into Nova’s phone to track her location. The woman tells Miles that he is Skizm’s most viewed player, and viewers have dubbed him “Guns Akimbo”. Miles rushes to the location and finds Riktor and the three goons there. They appear to shoot Nova in the head to taunt Miles, but he removes the bag off their head to see that it’s Hadley.
Miles goes to another location out in the open where Nix finds him and appears to shoot him dead. Viewers appear disappointed in Miles’s death. He is brought in by a clean-up crew to Skizm Headquarters, where Miles shoots two of the villains in the head. Nix then meets him there as they planned. We rewind to right before the shooting where Miles had waited for Nix to reveal that he knows Riktor killed her family, and shows her Degraves’s body. They teamed up to take Skizm down together, and set Miles up to wear a Kevlar vest. The two reveal themselves to the camera to let Riktor and viewers know that they are alive and coming for them, but Miles also takes an opportunity to tell everyone watching how screwed up they are for encouraging all this (not that they care).
Dane and Effie come down to kill Miles and Nix. Effie pins Miles down, but he manages to shoot her in the head. Dane severs two of her fingers and almost bashes her with a hammer, but Nix snorts some drugs and gets powered up, taking the hammer and smashing Dane’s bones. He tries to blow them up with a gas tank, but Miles comes in to finish the job, even though Nix told him not to. More henchmen go after them as Riktor tries to take Nova with him on a chopper. With the odds not in their favor, Nix decides to go out on her own terms after telling Miles to kill Riktor for her. She runs out shooting the henchmen while getting shot herself before running up to Fuckface while strapped with explosives, blowing herself, Fuckface, and every other goon to kingdom come.
Miles follows a message left by Nova to lead him to the roof. He catches Riktor before they get away, and he wastes his last bullet trying to shoot Riktor. He shoots Miles three times, but he continues moving toward him. Nova manages to free herself, and Miles pistol-whips Riktor before throwing him over the ledge. As he hangs on, Riktor tells Miles that Skizm is going to go global as a major franchise. Miles loosens Riktor’s grip and sends him plummeting to his death. Viewers everywhere cheer Miles’s victory. He has a brief fantasy where Nova runs back to him, but this is due to major blood loss, and she is actually horrified to have seen him kill Riktor.
Later on, Miles gets the guns removed from his hands. While he and Nova don’t get back together, she has created a “Guns Akimbo” comic book based on him, portraying him as a hero. He is now tracking Skizm activity across the world, making it his duty to take them all down.