Hidden in their cramped, overheated Parisian garret, the siblings grapple with their forbidden desires. Francine, haunted by Catholic guilt, tries to resist Pierre's allure. But his proximity, the heat, and their shared loneliness prove too much. She tentatively reaches for his cock, her fingers tracing its length. Pierre, eyes closed, lets out a low groan. Francine, emboldened, takes him into her mouth, her tongue exploring his sensitive tip. They move in sync, their rhythm building, until Francine impales herself on his cock, riding him with wild abandon. Their cries fill the room as they climax together, their bodies slick with sweat and spent passion.