The film opens in 2016 B.C. with Sarman (Hrithik Roshan), a young man from the ancient village of Amri, who lost his parents when young. Sarman's uncle gives him an amulet that contains an inscription of a unicorn Sarman sees in his dreams. This animal is also the emblem of the city of Mohenjo Daro.Arriving in Mohenjo Daro to sell his wares, Sarman learns that the city is ruled by the tyrant chief Maham (Kabir Bedi) and his wicked son Moonja (Arunoday Singh). Maham proposes to impose an additional tax on the farmers, but Sarman leads the farmers to oppose the taxes so that their families don't starve. Sarman gains access to the upper city by showing his uncle's amulet and falls in love with Chaani (Pooja Hegde), daughter of the head priest of Mohenjo Daro. The head priest, strangely, appears to recognize him. Chaani reveals that she has been forcibly betrothed to Moonja. Maham realizes Sarman and Chaani love each other and that Sarman is the leader of the tax revolt. Realizing that the people are rallying behind him, Maham gives Sarman the Bakar-Zokhar (Casey Frank, Michael Homik) challenge. Sarman proposes that if he wins, Chaani will be released from her engagement. It is accepted.The head priest reveals to Sarman how Maham was expelled from Harappa for illegal trade with Sumerians. Maham entered Mohenjo Daro as a trader and quickly rose to become the trade chief. Maham had discovered that the mighty Sindhu river held vast gold deposits so he decided to dam the river and divert its course to mine the gold. The wise Senate Chief Srujan (Sharad Kelkar) opposed this but Maham built the dam anyway and had Srujan framed and arrested for hoarding gold. Chaani's father and Durjan (Nitish Bharadwaj) - Sarman's uncle - were threatened by Maham to go against Srujan, and Srujan was killed. Maham then took his place as the new Senate Chief. The head priest then reveals that Sarman is Srujan's son. It is now up to Sarman to purge the evil Maham.Sarman faces the ferocious Tajik mountain cannibals Bakar and Zokhar in an arena before the city. After a vicious battle, he kills one of the cannibals but spares the other and the people of Mohenjo Daro surge even stronger behind him. Enraged, Maham urges Moonja to finish off Chaani and the priest. Moonja kills the priest but Sarman saves Chaani and kills Moonja.Chaani exposes Maham's plan to use the gold from the Sindhu to enrich himself and to smuggle in weapons from the West. All the chiefs now stand against Maham. The people elect Sarman as the new chief but Sarman suggests Mohenjo Daro needs a people's government, not a chief. Sarman realizes that the dam will burst and the Sindhu River will flood the city. He rallies the people to lash boats together and form a floating bridge. They evacuate Mohenjo Daro and cross to the other side of the river. The dam collapses, and Maham, chained in the city square, is drowned. The once renowned Mohenjo Daro is no more. The survivors migrate to another river, which Sarman names Ganga.