Sometime in the 15th Century, Sire of Coucy, friend of the debonair sire of Vergy, is also the lover of his friend's wife, the beautiful Gabrielle. The lovers plot to send Vergy to the Crusades by asking Millepertuis, a crusader, to convince him. Vergy is not as stupid as he looks but feigns to leave while entrusting Vergy with the key to his wife's chastity belt. During his absence, the illegitimate couple actually gets bored and they are relieved to see the husband come back six month later. From his fake Crusade, Vergy brings back two impertinent prisoners and beautiful Princess Mitzy, all three actually actors hired for the day. To cover his lie, he says that Millepertuis is dead and thus could not come back with him from the crusade. Yolande of Millepertuis decides to remarry with Count Maxime. Coucy surprises Vergy flirting with Mitzy (whose real name is Adèle) and, shocked, gives him back the key of the belt. Millepertuis comes back and Coucy understands that Vergy lied. He ...