An enterprising clerk leads the British colonial campaign in India.

In 1748, at Fort St. David, India, the French, Dutch, Portuguese and British are competing to establish trading posts. Robert Clive, a frustrated clerk for the East India Company, which enjoys the protection of the British government, proposes marriage in a letter to Margaret Maskelyne after seeing her picture in a locket worn by a fellow clerk, her brother Edmund. After word arrives that the French have attacked, Clive, a malcontent who believes in destiny, joins the British Army. When the entire British forces face almost certain annihilation at Trichinopoly, Clive escapes and convinces Governor Pigot to let him lead the remaining men to attack Arcot, the capital of Southern India, to divide the enemy forces. Clive succeeds and in less than a year becomes the conqueror of Southern India. Before a reception in his honor, Clive meets Margaret, but now that Clive is a hero, she does not want him to feel obligated to marry her. Clive, however, proposes and they return to England. Later, after Clive loses his seat in Parliament and all his money in the election campaign, and the doctor tells Margaret that their baby son will die within months, they return to India where madman King Suraj Ud Dowlah of Northern India has killed one hundred and forty-six English subjects by suffocation in the Black Hole of Calcutta. Clive forges the name of Admiral Charles Watson to a treaty with Suraj Ud Dowlah's uncle, Mir Jaffar, because the timid admiral hasn't the courage to sign, and after receiving encouragement from Margaret, he launches a surprise counterattack with far inferior forces against Suraj Ud Dowlah. The enemy counters using battle elephants, but Mir Jaffar's forces arrive and destroy Suraj Ud Dowlah's. Mir Jaffar, now king, presents Clive with a gift that allows him to retire to England. Years later, Governor Pigot calls on Clive to return to India where chaos now reigns due in large part to the flagrant abuses of the East India Company directors. Although Margaret strongly objects and predicts that her husband's success will end in disaster, Clive goes there and quells the situation, but the dismissed officers of the trading company launch a smear campaign against Clive charging that Mir Jaffar's gift was a bribe. Clive returns to face trial at the House of Commons and waits for the verdict at Queen's Square, his and Margaret's modest first home, where, despite their falling out, she visits and comforts him. The prime minister arrives and says that although the House condemned him, his fortune is safe and his honor intact, and conveys a message of gratitude from King George for adding great new dominions to the British Empire.