"Quite a simple farm girl, any innocence Isabelle once had has been kicked out of her. She is ready to die for the cause as long as she takes down three or four Germans with her."
— Call of Duty 3 description
She helps Ingram, Keith, and James Doyle in taking out several Flak guns in the countryside, and taking out a Nazi fuel plant, helping the Polish 1st Armored Division to gain an advantage over the Black Baron. She also helps Keith and Doyle free some Marquis being held hostage, including Major Ingram after a heated argument between LaRoche and Keith. As they were about to leave the town, an armored Nazi car comes to the town square with reinforcements and lays suppressing fire on the Marquis. Isabelle volunteered to take out the car while being covered by Doyle. As she finished planting the charge, she was killed when it detonated early.