On a trip to Paris with her husband, Isabella gave embroidered purses to her three sisters-in-law. These purses were later seen in the hands of two knights, prompting Isabella to assume adultery had been committed. It was called the Tour de Nesle Affair as the three women were said to have had the amorous relations with the knight in the Nesle Tower. The knights in question were "broken on the wheel, skinned alive, castrated, hanged on the public gallows of Pontoise, and finally beheaded."
The three sisters-in-law were "shaven, shorn, stripped of their royal robes, and imprisoned."