Two 18-year-old siblings, left alone, explore their forbidden desires. The sister, with her lithe body and innocent face, tentatively touches herself, her fingers dancing over her wet pussy. The brother, unable to resist the sight, joins her, his thick cock hardening. They masturbate openly, their eyes locked, the air thick with lust. Just as they're about to cross the final boundary, a creaking floorboard pierces their trance, forcing them apart.