The deadly dimensions over London have been sealed, and the monsters have departed. But word has come to Sherlock Holmes and Dr. Watson of a more terrifying creature still - the great Cthulhu has been sighted off the waters of Innsmouth, Massachusetts. Only Holmes can defeat him.And in the muddy village of Innsmouth, surrounded by villagers who are more sea-monster than human, Holmes meets again his nemesis, Moriarty, and yet greater foes: Amelia Scarcliffe and Maria Fitzgerald, harbingers of Dagon, who have called forth Cthulhu. Their task: to bring about the end of humankind, and begin the realm of nightmares on Earth.