The siblings' secret game begins as they negotiate a price. "Five hundred for a blowjob," he says, his voice steady despite his racing heart. She agrees, kneeling down, unzipping his jeans. She takes his cock out, licking her lips, "And what about full sex?" she asks, her breath hot on his dick. He swallows hard, "A thousand." She smiles, leaning in, "Deal," she whispers before taking him into her mouth. The camera rolls, capturing their forbidden transaction, their bodies entwined in the dim light of the closet.