In the gritty gyms of post-war Zaragoza, Martín Baumer—once a promising boxer—is now a broken sparring partner with nothing left to fight for. But when an old friend calls with a plea that reeks of desperation, Martín boards a train to Madrid, stepping into a web of betrayal and blood. A single moment at a warehouse changes everything: a stabbing in the crowd, a body in his arms, and a city ready to condemn him. With no witnesses and no way out, Martín must face the toughest opponent of his life—his past.