In Black Butler: Book of the Atlantic, the Black Butler, Sebastian Michaelis, and his young master, Ciel Phantomhive, join a luxury liner on a voyage in pursuit of an elusive, mysterious man who holds the key to eternal life. As they investigate the supernatural events occurring on the ship, they encounter reanimated corpses and unearth the secrets of the legendary Campania.

When a series of murders plague the aristocracy, Ciel and Sebastian must uncover the truth behind the shocking crimes. As they delve deeper into the investigation, they find themselves caught in a web of deceit, betrayal, and supernatural occurrences. With their lives at stake, they must navigate the treacherous world of the elite and unmask the killer before it's too late.