In the quiet of his room, a young man, alone and curious, tentatively explores his body. He tentatively strokes his hardening cock, his breath hitching as he discovers new sensations. His mind wanders to taboo thoughts, his sister's body, her laughter, her scent. He feels a pang of guilt but pushes it aside, lost in the rhythm of his hand. His strokes grow faster, his grip tighter, until he finds release, his cum spilling out, staining his sheets with his secret.