In Victorian England, Ciel Phantomhive is a young aristocrat who leads the powerful Phantomhive family and serves directly under the Queen. Behind his cold appearance and noble status lies a past marked by violence and a deep desire for revenge. To achieve his goal, Ciel has made a contract with Sebastian Michaelis, a demon who now serves as his butler. Together, they investigate criminal cases, disturbing phenomena, and conspiracies involving high society, the occult, and family secrets, while the price of the pact between master and servant remains constantly present.