The stepbrother begins to notice his mother in a new light after a friend comments, "Your mom is really hot." One night, he ends up raping his mother while she's masturbating, and from that moment on, he becomes obsessed with abnormal sexual training. He treats her like a dog, binds her with restraints, and relentlessly torments her with sex toys. Yet, the mother's body responds to the humiliation, moaning and reacting in ways that further shatter his sanity. Though both know it's wrong, their twisted relationship deepens, and the intensity of the training escalates beyond control.