Set in late 19th-century Pennsylvania, this gripping social drama tells the story of an undercover detective (Richard Harris) sent to a coal mining community to expose a secret society of Irish-American miners battling exploitation at the hand of the owners. Based on a true story, the film accurately portrays the rebellious leader of the Molly Maguires (Sean Connery), and his will to stop at nothing--even murder--to achieve social justice.