The Underworld

As discovered in Season 2.

The Underworld is a twilight world that is part of our world and part of the netherworld itself. Partially a land the dead go to rest and partially under our physical world.

When visited by the living the physical side of the world is visible but there like a dream... or nightmare. Whichever it may be, nothing is as it seems. A unique realm where the physical and spiritual exist in the same space.

Souls can be found here in the dark realm of The Ferryman and if worthy can return, for a price. For even the ferryman has to follow his own laws.