A woman searching for a sister lost at sea. A man bent on finding lost treasure. A mother who has lost all hope. A maniac who believes all life exists for his pleasure. The man who would keep them all safe. Together, they will all seek below the waves for treasures long buried, and riches beyond belief. But those treasures hide something. Something ancient, something dark. A creature that exists only to feed on those that would enter into its realm. A creature... of The Deep.

Twenty-five years ago, Maggie Holt and her parents, Ewan and Jess, moved into Baneberry Hall, a rambling Victorian estate in the Vermont woods. Three weeks later they fled in the dead of night, an ordeal Ewan later recounted in a nonfiction book called House of Horrors. His horror memoir of ghostly happenings and encounters with malevolent spirits became a worldwide phenomenon, rivaling The Amityville Horror in popularity — and skepticism.

Two sisters on trial for murder. They accuse each other.

Lifestyle journalist Katrine escaped past traumas by moving to a coast renowned for seaside holidays and natural beauty. But when a vast hoard of human remains and prehistoric artifacts is discovered in nearby Brickburgh, a hideous shadow engulfs her life. Helene, a disillusioned lone parent, lost her brother, Lincoln, six years ago. Disturbing subterranean noises he recorded prior to vanishing, draw her to Brickburgh's caves. A site where early humans butchered each other across 60,000 years. Upon the walls, images of their nameless gods remain.

Evie Childs hoped the all-expense-paid trip to Africa would give her a chance at adventure. Maybe it would even let her forget a past that haunts her and find safety from a husband who abuses her. But when a group of "freedom fighters" kidnaps her safari tour group, intent on holding them for ransom, the adventure turns to nightmare. Now, Evie and the rest of the survivors must travel across miles of the harshest, most dangerous environment on Earth. No food. No water. No communications. And they're being hunted.