The film revolves around Balraj Kapoor (Amitabh Bachchan), a rich businessman happy with his life. He has a loving wife Shobhana (Hema Malini) and an ideal son Avinash (Salman Khan), who is studying abroad.
Avinash completes his education and decides to return home, much to his parents' joy.
Soon after coming back, Avinash meets Malvika 'Milli' Talwar (Rani Mukerji) and gets married to her. They have a son and call him Ansh.
However, this happiness is shortlived because tragedy strikes the family. Avinash is killed in an accident and an inconsolable Milli is unable to accept this loss and slowly goes into depression.
Balraj decides to bring Milli out of her abyss of grief. He goes to meet Milli's old friend Rajat (John Abraham), who has always loved her but never expressed it. Balraj asks Rajat to marry Milli but faces opposition from his conservative elder brother Balwant (Om Puri), who doesn't believe in widow remarriage.
Will Balraj succeed in uniting Rajat and Milli?
With Sooraj Barjatya's "Vivah", about the sanctity of marriage, doing brisk business at the box office, expectations are high from Chopra's "Baabul".