The film begins in 2016 B.C., introducing us to Sarman (Hrithik Roshan), a young man from the ancient village of Amri, who tragically lost his parents in his youth. Upon receiving an amulet from his uncle, which features an inscription of a unicorn—the creature that appears in Sarman's dreams—he sets out for Mohenjo Daro to trade his goods.
Upon his arrival, Sarman discovers that the city is under the oppressive rule of the tyrant chief Maham (Kabir Bedi) and his malevolent son Moonja (Arunoday Singh). Maham proposes an unbearable new tax on the farmers, prompting Sarman to champion their cause in a bid to prevent their families from starvation. Armed with his uncle's amulet, he gains entry to the upper city and quickly falls for Chaani (Pooja Hegde), the daughter of the head priest of Mohenjo Daro. Unbeknownst to Sarman, Chaani is already betrothed against her will to Moonja.
Realizing the deep connection between Sarman and Chaani, Maham becomes increasingly threatened. He then issues Sarman the Bakar-Zokhar challenge, betting that if Sarman wins, Chaani would be freed from her engagement. This challenge is accepted with much anticipation.
The head priest unveils the dark history behind Maham's rise to power; he was banished from Harappa for illegal dealings with the Sumerians. Under the guise of a trader, Maham took control of Mohenjo Daro, discovering the wealth hidden within the Sindhu River. Determined to extract the gold, Maham dammed the river, defying the wise Senate Chief Srujan (Sharad Kelkar), who opposed his greed. Framed by Maham's treachery, Srujan met a tragic fate, allowing Maham to assume his position. In a shocking twist, the head priest reveals that Sarman is indeed Srujan's son, tasked with ending Maham's reign of terror.
In a gripping arena duel, Sarman confronts the fearsome mountain cannibals, Bakar and Zokhar. After a fierce battle, he defeats one but chooses to spare the other, galvanizing the people of Mohenjo Daro to rally behind him. In a fit of rage, Maham incites Moonja to eliminate Chaani and the priest. He manages to kill the priest, but Sarman intervenes just in time to save Chaani and avenge the priest by taking Moonja's life.
Chaani reveals Maham's sinister plans to exploit the gold from the Sindhu for his own gain and smuggle in weapons. This revelation unites the chiefs against Maham, and in a moment of great honor, the citizens elect Sarman as their new chief. However, Sarman humbly advises that the city doesn't need a sovereign rule, advocating instead for a people's government.
As the threat escalates, Sarman foresees the imminent disaster of the bursting dam, which will flood the city. He spontaneously organizes the citizens to bind together their boats into a makeshift floating bridge, enabling a mass evacuation across the river. As they escape, the dam collapses, drowning the treacherous Maham, who is shackled in the square. With the mighty Mohenjo Daro succumbing to the waters, Sarman leads the surviving community to a new beginning, giving the river a new name: Ganga.
