The Hotel del Luna (formally referred to as the "Guest House of the Moon"), located in Seoul, is not like any other hotel: its clients are all ghosts and is not visible in its true form during the day. During the Goguryeo era, a rebel named Jang Man-wol (Lee Ji-eun) drank a liquor that unknowingly turned her into the guest house's owner while she was traveling to find it. She has been stuck running the hotel for the past millennium before meeting Ku Chan-Seong (Yeo Jin-goo), the new manager.