Orphaned and abused at a very young age, a young boy struggles to make a living by slaving day and night, working in the house of a wealthy man named Ramnath. Ramnath does not like him: it is later revealed that another orphan had taken advantage of his kindness in the past, hence his animosity. Ramnath's young daughter Kaamna, however, empathizes with the boy and they form a friendship.
Eventually he is adopted by a Muslim woman who also works for Ramnath, Fatima, who decides to name him Sikandar. On the occasion of Kaamna's birthday Sikandar, who had promised to replace one of her dolls which he'd broken, steals an expensive doll from a shop to give as a gift.
However, Ramnath refuses to let the boy attend the party, and when Sikandar breaks into Kaamna's room to deliver the doll, he is caught and accused of trying to rob the house. He and his mother are banished from Ramnath's home. Shortly thereafter, Fatima dies, leaving young Sikandar with the responsibility of looking after her daughter, Mehroo.
As Sikandar is crying in the graveyard, a fakir comes to him and asks him to embrace the woes of life and find happiness in sadness, for then he would become the conqueror of fate. The sequence cuts to a grown up Sikandar (Amitabh Bachchan) zooming on his motorbike singing his favourite tune. It is then revealed that Sikandar has amassed a fortune by turning in smuggled goods to the police and receiving the reward payouts. With all his wealth he has managed to build an impressive house for himself along with setting up a profitable business.
Sikandar still has not forgotten Kaamna (Raakhee) from his childhood. She and her father have fallen on hard times, and Sikandar is anonymously supporting them. Eventually he gets up the nerve to try to talk to Kaamna, but she still believes that he betrayed her family, and she snubs him. Sikandar is upset by the refusal and becomes a heavy drinker. He also visits Zohra Begam's (Rekha) kotha on a regular basis.
One night in the bar Sikandar meets up with Advocate Vishal (Vinod Khanna) and a friendship is formed between them when Vishal risks his own life to save Sikandar from a bomb blast. Sikandar introduces Vishal to Ramnath and the two begin to work together.
Zohra eventually falls into an unrequited love with Sikandar, and this in turn angers Dilawar (Amjad Khan) a hard core criminal who loves Zohra and will kill any one who lays an eye on her. Upon finding that Sikandar is frequently visiting Zohra, Dilawar confronts Sikandar and in the ensuing fight is thrashed by him. He swears to kill Sikandar.
Kaamna discovers Sikandar's kindness to her family and goes to thank him. Encouraged, Sikandar tries to profess his love to Kaamna through a love letter. Because Sikandar himself is illiterate, Vishal transcribes the letter for him, but the plan backfires when Kaamna mistakes the letter as actually being from Vishal.
Vishal, unaware that Kaamna is the girl Sikandar loves, reciprocates her love, and the two begin to date. Sikandar, upon learning this, struggles with his emotions but decides he must sacrifice his love for the sake of his friendship with Vishal. Vishal and Kaamna plan to marry.
Sikandar's visits to Zohra have hampered his reputation, and the upcoming marriage of his sister Mehroo is at risk of being cancelled over his behavior. Vishal, knowing Sikandar won't change, visits Zohra and offers to pay her if she will abandon Sikandar. Zohra, upon learning the reason, promises Vishal that she would sooner die than let Sikandar visit her again.
Later, Sikandar arrives at Zohra's and she refuses to let him in. Sikandar demands entry, and when Zohra is unable to stop him she kills herself by swallowing a diamond, and dies in his arms.
Dilawar in the meanwhile has formed an alliance with Sikandar's arch enemy, JD, and upon learning of Zohra's death hatches a plan to destroy Sikandar and his family. Kaamna and Mehroo are both preparing for their weddings; JD and his henchmen kidnap Sikandar's sister Mehroo but Vishal follows them and rescues her. Dilawar kidnaps Kaamna, but Sikandar follows him.
He rescues Kaamna and sends her home while he battles Dilawar. In the final battle both Dilawar and Sikandar are mortally wounded, and Sikandar tells Dilawar that he never loved Zohra. A dying Sikandar reaches the wedding of Kaamna and Vishal. Just as the wedding ceremony is completed, Sikandar collapses. His dying words inadvertently reveal his love for Kaamna, and Vishal sings him his favourite song, "Life is going to betray you someday...Death is your true love as it'll take you along..." Sikandar's entire life flashes before him and he dies in Vishal's arms just as the song is completed.