The Unholy Trinity - Origins (Book 1 of The Unholy Trinity)

Six of the seven seals of the Apocalypse are broken.

The key to breaking the last seal is a half demon named Katie, a succubus who doesn't know what she is, with a power she can't control.

Coming to her aid is Rebecca, a teenage necromancer whose dad has gone insane. And Jacob, a two thousand year-old demon seeking redemption for his sins.

The odds are against them, but these three unlikely companions may be all that stands between the world and its destruction.