A British officer is falsely accused of murder by a rival officer, and is dishonorably discharged from the army. He rejoins as an enlisted man and is posted as a cavalryman to the siege of Sebastopol during the Crimean War. He discovers that there is a Russian spy masquerading as a British soldier, and his efforts to unmask the spy results in the famous Charge of the Light Brigade to take the Balaclava Heights.