In 2020, human boxers are replaced by robots. Charlie Kenton (Hugh Jackman), a former boxer, owns "Ambush", but loses it in an arranged fight against a bull belonging to promoter and carnival owner Ricky (Kevin Durand), who sees Charlie as a joke, partially because he beat Charlie the last time they competed in the ring. Having made a bet that Ambush would win, Charlie now has a debt to Rickyâwhich he runs out on.
After the fight, Charlie learns that his ex-girlfriend died and he must attend a hearing deciding the future of their son, Max (Dakota Goyo). There, Max's aunt, Debra (Hope Davis), and her wealthy husband, Marvin (James Rebhorn), request full custody, which Charlie concedes for $100,000, half in advance, on the condition that Charlie retains Max for three months. Thereupon, Charlie, Max, and Bailey Tallet (Evangeline Lilly), the daughter of Charlie's former boxing coach, acquire the once-famous "Noisy Boy" and arrange a fight, where he is destroyed by "Midas". Attempting to scavenge parts of a new robot from a junkyard, Max discovers "Atom", an obsolete but intact sparring robot designed to withstand severe damage, and capable of mirroring its handler's movement due to its rare "shadow function" module.
At Max's behest, Charlie pits Atom against "Metro", whom Atom overcomes. Max convinces Charlie to control Atom, resulting in a series of victories and culminating with the defeat of national champion "Twin Cities". Elated by their success, Max challenges global champion "Zeus". After the fight, Ricky and his two henchmen attack and rob Charlie of his winnings, which prompts him to return Max to Debra. While talking with Bailey about the events, the two kiss, revealing their attraction to each other. Persuaded by Bailey, Charlie arranges the challenge offered by Max and convinces Debra to allow Max to witness the fight.
During the fight, Atom's vocal-respond controls are damaged, forcing Charlie to activate its "shadow function" to make it mimic his boxing skills. Zeus's programmers are unable to compensate, forcing the owner to take control like Charlie has. Zeus is given a sound beating, but wins the match since Atom couldn't beat it within the time limit. Zeus remains "undefeated", but with the shame that it came from a technicality. Atom is labelled the "People's Champion".
Who is Max's aunt?
Debra