British army doctor Robert Lowndes battles a cholera epidemic at a small fort in Cawnpore, India, in the 1850s. When he catches a fever he begins to take morphine in order to continue treating his patients. Unfortunately he becomes an addict. He is supported by his girlfriend Betty Archer, but a rival suitor, Capt. Guy Douglas, is determined to get Lowndes out of the picture any way he can, including giving him drugs. Matters are further complicated by the outbreak of the Sepoy Rebellion, a nationwide mutiny of Indian soldiers in the British army, which breaks out in Cawnpore.