Shen Jiahe accidentally falls into a horror dungeon and discovers that the notoriously terrifying ultimate boss, the Warden, is none other than her lost boyfriend, Lin Yuanzhou. From the Island Prison to the Doll Manor, from the Twin Villa to the Forest Orcs, Lin Yuanzhou accompanies her in different avatar forms across successive dungeons, while all the eerie entities in every dungeon unanimously address her as "Sister-in-law" to escort her. Relying on her wit to break through the game, she shares sweet moments with the love-brain boss in dangerous situations, kicking off an alternative dungeon adventure intertwined with thriller and sweet romance.