Balaguer, 1938. The Civil War rages furiously across the Segre, but Xavier feels safe and each day he takes his bicycle out to explore the town and its surroundings. In one of his trips he meets Matthew, a sixteen-year-old boy who is the son of an anarchist and is about to join the front. When Xavier, son of an engineer under the order of Franco, discovers the secret weapon that helped his father prepare to wipe out the Republican side, it will pose the most critical dilemma of his life.