Bob Biswas, Abhishek Bachchan wakes from an eight-year coma after being hit during the Kahaani events, and he cannot recall anything—not even his wife Mary Biswas Chitrangada Singh or their children Mini Biswas Samara Tijori and Benny Biswas Ronith Arora. Two Kolkata Police officers, Jishu Narang Bhanu Uday and Kharaj Sahu Vishwanath Chatterjee, shadow him, keeping a close eye on a man who, unknown to him and his family, leads a double life as a professional killer.
Under their covert arrangement, Bob is recruited to become a dedicated hitman for a mysterious force. They hand him a flip phone that transmits photos of his targets, pulling him deeper into a world of contract killings. Meanwhile, Mini faces a dangerous temptation of her own, as she becomes addicted to a drug called Blue, distributed by Bubai Da Purab Kohli and his boss, Ustaad Kaushik Raj Chakraborty. After Bob’s first target photo arrives, he visits Kali Da Paran Banerjee, a homoeopathy pharmacist who also runs a pistol disguised as Nux Vomica. With Kali Da’s help, Bob acquires the weapon and eliminates Bubai and two of his accomplices, then heads home and crosses paths with Mini, who has just bought Blue—unaware that Bob is the man behind Bubai’s death.
Bob’s second target turns out to be Rahul, an investor connected to Ustaad who is revealed to be an undercover police officer investigating Ustaad’s drug network. Inspector Indira Verma Tina Desai begins probing the murders of Bubai and Rahul, while Ustaad’s operations receive on-the-ground scrutiny from his henchman Dhonu Pabitra Rabha. Dhonu, who is close to Bob’s family and frequents his noodle stand, starts to dig into the killings as well. In a pivotal moment, Bob revisits the grave of Mary’s first husband, David, and recalls a diary that contains names of targets, who paid for them, and the money trail. From this diary, he uncovers a key and a sense of purpose beyond fear.
Bob’s third target is Indira Verma’s boss, but after a meeting with Indira, she reveals that her boss plays a role in combatting the drug mafia, and Bob chooses not to kill him. Jishu and Kharaj confront Bob about why he skipped the third strike, and Bob warns that he will turn himself in to Indira Verma with the diary if they push him further. They go to Ustaad’s circle, where Bob also seeks out Kali Da to return the Nux Vomica and obtain the key that could unlock more secrets. Kali Da then leads him to a trunk room in his shop, revealing a carrier bag stuffed with cash—enough to offer his family a chance at a new life in Kalimpong.
With the money in hand, Bob fulfills his obligations to Kali Da and heads home. It’s soon revealed that Boss, Jishu, and Kharaj are all connected to Ustaad. Ustaad orders Dhonu to kill Bob, but Dhonu refuses and is killed by one of Ustaad’s men. Night-time, two of Ustaad’s henchmen break into Bob’s home, torturing him and breaking his right hand, while Mary and Benny are killed in the struggle. Bob fights back fiercely and kills both assailants.
Indira Verma arrests Bob, but her superior orders his release. Bob then goes to confront Jishu and Kharaj and, in a brutal encounter, kills Kharaj. He moves on to Ustaad’s location and wipes out several of Ustaad’s henchmen. Ustaad—also known as Doctor Uncle—reappears with Mini, who is now deeply addicted to Blue and urged to kill Bob in exchange for more of the drug so she can pass exams and become a doctor. Ustaad confirms that he ordered the murders of Mary and Benny and, after a desperate struggle, Bob finally kills Ustaad.
Six months pass, and Bob and Mini visit the graves of Mary and Benny; the atmosphere remains tense, with Mini not fully forgiving him. After Mini leaves, Bob receives a photo of a new target on his phone and accepts the assignment with a quiet, determined resolve. The cycle of violence seems to march on, but the night horizon hints at a different path for Bob and his daughter—one that may or may not diverge from the shadowy code he has followed for so long.
