The film begins in 1857, when India was ruled by the British East India Company. Mangal Pandey (Aamir Khan) is a sepoy, a soldier of Indian origin, in the army of the East India Company. Pandey is fighting in the Anglo-Afghan Wars and saves the life of his British commanding officer, William Gordon (portrayed by Toby Stephens). Gordon is indebted to Pandey and a strong friendship develops between them, transcending both rank and race.<br/><br/>Gordon rescues a young widow, Jwala (Ameesha Patel), from committing Sati (the act of following her deceased husband on to the funeral pyre). Afterwards, he falls in love with her. Meanwhile, Heera (Rani Mukerji) has been sold into prostitution, to work for Lol Bibi (Kirron Kher). There is a spark of attraction between her and Pandey and a liaison follows.<br/><br/>Gordon and Pandey's friendship is challenged following the introduction of a new rifle, the Enfield rifled musket. In reality as in the film, rumors began to spread among the sepoys that the paper cartridges that held the powder and ball for the rifle were greased with either pig fat or beef tallow. Since the process of loading the cartridge required the soldier to bite the cartridge open to pour in the loose powder, the soldiers believed that the process would require them to consume pork or beef - an act abhorrent concept to Muslim and Hindu soldiers, respectively, for religious reasons.