Mike's world stops as he pushes open River's bedroom door, catching her in the throes of self-pleasure, her petite form writhing on the bed. Her small, perky tits heave as she gasps, her hand buried between her legs. Mike's cock stiffens at the sight of his innocent stepsister's taboo masturbation. He can't help but imagine his thickness stretching her tight pussy, her moans echoing through the house. Their eyes meet, and the air crackles with tension.