One day, countless dungeons suddenly appeared in the world, and humanity ushered in the "dungeon era". Adesalai, the boss of an abyss-level dungeon, was killed by human adventurers via despicable means. Vowing revenge, he was reincarnated as a weak adventurer, but he activated an exclusive Boss System. Using the system's cheating powers to conquer dungeons and becoming its master, he started on the road of revenge.