Hyun-su and Soo-jin are newlyweds. Seemingly out of nowhere, he starts talking in his sleep: ‘Someone’s inside.’ From that night on, whenever he falls asleep, he transforms into someone else with no recollection of what happened the night before. Soo-jin is overwhelmed with anxiety that he’d hurt her family while she sleeps and can barely sleep a wink because of this rational fear. Despite sleep treatment, Hyun-su’s sleepwalking only intensifies, and she begins to feel that her unborn child may be in danger…”