Luke Bonapart has a dream: to obtain the legendary treasure, "Dream's End," located at the bottom of Noah's Great Labyrinth and become an S-rank adventurer like his parents, who were killed by the 50th-floor boss. His only skill is "Laundry," given to him by God on his 7th birthday. Despite his useless skill, he endures slave-like treatment and strives to achieve his dream. Betrayed and left to die by his childhood friend, Kyle, he's saved by Lucifer, a fallen angel imprisoned in the dungeon. Lucifer's sins are cleansed by Luke's Laundry skill, transforming her back into an angel. Luke's Laundry skill can apparently cleanse anything. This is the story of Luke, the fallen angel Lucifer, and the young dragon girl Ashley, as they conquer the dungeon together.