Wriothesley is a successful private police officer who, along with his subordinate Cloride, has been tasked by the OOST (Order of Obsidian Secrecy of Tayvat) to track down the most dangerous mafia in Tayvat, known as the "Poisoned Syndicate". Unfortunately, the only information they have is the nicknames of the boss (Ventteda) and the soon-to-be boss (Hydra). They have no further details about them, except for the cases that could be connected to this notorious criminal organization, recognized worldwide.