In Arkham, Dan Upton is worried that his friend Edward Derby is being led into a cult like group by his new girlfriend Asenath Waite. Meanwhile, Inspector LeGrasse investigates a spate of bizarre killings around the town, in which the victims have been decapitated and drained of blood. LeGrasse believes the murders may be linked to a Cthulhu cult active in the nearby towns of Innsmouth and Dunwich - that was headed by Asenath's late father Ephraim Waite. As Edward begins to behave more and more strangely, Dan and LeGrasse go to Miskatonic University to seek the help of Professor Armitage an expert in weird cults and ancient myths.