In the quiet of their home, a curious, innocent sister and brother stumble upon each other's hidden desires. She, a naive virgin, discovers her brother's secret masturbation habit, and he, intrigued by her newfound curiosity, offers to guide her through her first time. With trembling hands, they explore each other's bodies, their pure intentions slowly morphing into a heated, forbidden passion. Their first time is a mix of raw, intense pleasure and overwhelming guilt, as they struggle to reconcile their newfound lust with their innocent upbringing.