Ajju Bhai, known as Aziz Ali, portrayed by Farhan Akhtar, is a goon working under the notorious Jaffar Bhai, played by Vijay Raaz. His violent lifestyle often leaves him beaten and bruised, landing him at the clinic run by Dr. Ananya Prabhu, represented masterfully by Mrunal Thakur. Ananya operates a charity hospital dedicated to assisting the marginalized, where she provides first-aid to Ajju after his many altercations. Accompanying her in this noble endeavor is Sister D'Souza, skillfully portrayed by Supriya Pathak, who believes that Ajju is merely a victim shaped by his circumstances.
As Ananya learns more about Ajju's compassionate side—especially his care for an orphanage—she begins to develop feelings for him. Ajju, meanwhile, finds solace in boxing, a passion ignited after visiting a gym managed by Merchant, illustrated by Deven Khote. Under Merchant’s influence, Ajju starts to appreciate the sport's values, inspired by legendary boxer Muhammad Ali. Parvez, another boxer and Merchant's student, introduces him to the boxing coach, Nana Prabhu, played by Paresh Rawal.
Initially hesitant due to Ajju's background, Prabhu eventually sees potential in him, allowing him to refine his boxing skills after Ajju demonstrates the raw power of his punches. Following weeks of intense training, Ajju impresses Prabhu, who then grants him entry into the boxing ring, despite the fact that Ananya has kept her identity as Prabhu's daughter a secret from Ajju. As their romance blossoms, so does Ajju’s boxing career. However, conflict arises when Prabhu discovers the truth about their relationship, creating tension due to his prejudice against inter-caste marriages rooted in personal tragedy.
After a fallout with Prabhu and the boxing community, Ajju finds himself in dire straits, resorting to fixing matches for money, which results in his ban from the sport for five years. While struggling to make ends meet, Ananya forgives Ajju after learning about the coercion behind fixing the matches and they marry, starting their life together. Their joy is bittersweet, as tragedy strikes when Ananya is killed in a terrorist incident, forcing Prabhu to confront his feelings of loss for his daughter.
Determined to honor Ananya's memory, Ajju seeks Prabhu's mentorship again, but initially faces rejection. Undeterred, he begins training on his own, pushing himself back into peak condition in preparation for the state championships. As he battles through challenges, he earns a spot in the Nationals, eager to prove himself against the formidable Prithvi Singh, a competitor from the Railways.
As tensions escalate, Prabhu uncovers corruption affecting Ajju's matches. Standing up for his protégé, Prabhu helps to clear Ajju's path to the finals. Facing Dharmesh Patil, who bears a grudge against him, Ajju must rely on his training and instincts to endure the match. The fierce bout tests his resilience, as he fights hard despite taking a barrage of punches. In a climactic turn, Ajju rises from the canvas to unleash a counter-attack, ultimately emerging victorious by knocking out Prithvi, fulfilling both his dreams and his late wife's wishes.
