Southwest England, 1812. England is at war with America, and when 250 American prisoners of war arrive at Dartmoor prison, it's already overcrowded with French inmates. Among the newcomers is Lieutenant Pilgrim Penn, an American merchant seaman, who soon falls in love with a local girl at a market held inside the prison walls. Despite their common enemy, the inmates fight amongst themselves, and the Americans are a particularly troublesome group. When the governor's daughter becomes romantically involved with one of them, he orders his soldiers to open fire during a minor disturbance - even though the war has ended and personal revenge is suspected as his true motivation.