The beginning of the Hundred Years' War. The young Count Theodor de Bongrais doesn't want to submit to the British who are rapidly conquering France and intends to put up an active resistance. He is betrayed and handed over to his enemies by the administrator of his castle, Don Pauline. Sentenced to death, he escapes from prison with the help of a trusted man and begins a fight with the hated enemy.

In this way, he exposes himself not only to the Black Prince and his henchmen, but also to his own countrymen, who try to somehow get along with the occupier. As Theo le Vengeur, he collects a small band of outcasts by his side he wages a ruthless guerrilla warfare. His faithfull followers are; Belette, a country girl with an uncommon mind, her brother Pierre, a former participant in the Jacquerie who hates the nobility, Berengard, a former castle servant, and many others who are equally committed to the cause...