Set in Pennsylvania coal country, the film tells the story of Joe Radek (Paul Muni), a miner of Slavic background. Upset after an argument with his girlfriend Anna Novak (Karen Morley), he drinks and attends a union meeting, where he acts as a catalyst to splitting the union members into radical and moderate factions; radically inclined miners decide to walk out and strike, the others led by Radek's best friend Mike Shemanski (John Qualen) stay at work. Meanwhile, the company brings in a private police force cobbled out of thugs by a Pinkerton (detective agency)-type detective agency.