John Biswas, played by Amitabh Bachchan, is a determined 70-year-old grandfather frequently visiting the police station in Kolkata, fueled by a fierce desire to uncover the truth behind the kidnapping and murder of his beloved granddaughter, Angela (Aarnaa Sharma). Eight years have passed since that tragic day, yet the case remains a haunting mystery for him. Inspector Sarita Sharma, portrayed by Vidya Balan, remains sympathetic but ultimately lacks any significant leads. Despite her assurances that she will notify him of any new developments, John's relentless pursuit of justice compels him to investigate independently, diligently collecting evidence despite the discouragement from those around him.
John's personal life is fraught with challenges, as his wife Nancy (Padmavathi Rao) battles illness and is confined to a wheelchair. Their daughter Angela was the child of John's son-in-law Peter (Tota Roy Chowdhury), who harbors a deep resentment towards John, blaming him for Angela's demise. John, however, steadfastly believes that it was the police's negligence that failed to protect his granddaughter. After the death of Peter's wife, John had taken it upon himself to care for Angela.
As John continues his quest, he frequently engages with Father Martin Das (Nawazuddin Siddiqui), a former police inspector who had initially overseen Angela's case. Haunted by his inability to solve the case, Martin had left the force and turned to a life of priesthood, yet he assists John in piecing together the puzzle of Angela's disappearance.
The story intensifies as John recalls the fateful day Angela was kidnapped—a day when she had decided to take an alternate route from school and was snatched away by a black van on a deserted street. Caught up in the memories, John listens to evidence tapes repeatedly, striving for insights.
One day, while at a fish market, John spots a young deaf and mute girl (Abhipriti Das) with a woolen cap resembling Angela's. Investigating further, John uncovers that the cap was donated by someone from Imambara, leading him and Father Martin on a journey to uncover more clues. Their pursuit leads them to an aluminum box buried on the property, which contains not only the cap but also a pen bearing an emblem of a swan—an emblem that resurfaces as a connection to John's past involvement with the Land Management Office while helping Peter acquire property.
With relentless determination, John discovers more about employees at the LMO who had left under suspicious circumstances following Angela's death. As the years glide by, another boy named Rony (Ricky Patel) is kidnapped in a case echoing Angela's abduction, reigniting John's fervor for justice. Together with Inspector Sarita, who now seeks Father Martin's help, they attempt to crack this latest case.
The tension rises as the kidnapper demands a ransom of Rs 20 Lakhs, paralleling John's ordeal with Angela years ago. With intertwined histories, John is drawn back into a web of deceit and betrayal, leading him to unearth the identity of Angela's kidnapper, whose roots run deep into his past.
In a climactic twist of fate, John orchestrates a dark plan of revenge, revealing that Manohar (Sabyasachi Chakraborty), Rony's grandfather, is also implicated in Angela's kidnapping. As the threads of the past unravel, John's investigation culminates in a confrontation with Manohar, uncovering the chilling truth about Angela's fate and clarifying that she was not murdered but had met an untimely tragic accident.
> "The pain of a grandfather becomes the resolution for justice."
John's unyielding spirit shines through, vowing not to rest until the truth about the heinous acts committed against his family is fully revealed, proving that the profound bonds of love and justice transcend even the cruelest of betrayals.
