John Biswas (Amitabh Bachchan) is a 70-year-old grandfather who visits the police station regularly. He is desperate to find the kidnapper and murderer of his granddaughter Angela, who died eight years ago. Police inspector Sarita Sarkar (Vidya Balan) has no clues about the case. But he continues to search for the person who caused it, despite being discouraged by people all around him, and collects evidence one by one at a slow pace.