The Ha family moves into Unit 444 of the Mysterious Apartment, a place notorious for paranormal activity and said to be the site of its most terrifying incidents. From their very first day, they find themselves constantly entangled in strange occurrences. They sense a bizarre presence in the clearly empty elevator, and thumping noises echo all night from the supposedly vacant floor above... Meanwhile, a little boy who crawled out of a manhole on the first floor approaches Hari and her younger sibling, Duri, repeatedly picking fights with them. After inadvertently snatching and eating the boy's candy, the two siblings begin to see the ghosts that reside in the Mysterious Apartment. The manhole boy reappears before the startled pair, boasting loudly that if they help him exorcise ghosts from now on, he will grant any wish they desire...