Elaine West is the sole survivor of a disastrous expedition from Miskatonic University to the wilds of Desolation Sound in British Columbia. She returns with an incredible tale, of madness, betrayal, and death… and even more ominous, of a creature beyond imagining known as Great Cthulhu. And her story is only slightly less believable than the identity of her travelling companion: Nikola Tesla, the greatest inventor of the age and the only person other than West to see the creature and live.
Now they must find allies among the disbelieving population of Arkham, because the scattered news reports of disappearances and strange sightings tell West and Tesla something that chills their blood and drives them to a desperate plan. The Cthulhu cult is moving and its destination is obvious: Arkham itself.