Set in an alternate 1950's America, witches, demons, and magic are real. Oliver, a bitter incubus, is accidentally summoned by Ava, a very forgetful witch, as her Familiar. Together, they must explore the far reaches of the world to obtain rare components to complete the ritual that would break their bond, setting Oliver free.
However, their adventure doesn't come without a price. A group known as the Harvesters are hunting witches like Ava down, and their leader seems to have taken an interest in the pair. Oliver and Ava must learn to work together while avoiding the Harvesters at all costs to see their journey through to the end.