After the confrontation with the triune, both Elizabeth and Lev are forever altered. Elizabeth no longer possesses the ability to kill angels. Lev is now human. Yet no action is without consequence. The void left in Elizabeth from that power has marked her and attracted much attention from dybbuks, rogue spirits left behind from sojourns gone wrong. They see Elizabeth as a conduit to return to the world of the living, no matter that such an act might destroy her.
Lev, on the other hand, has become completely mortal and is overrun by all the emotions he's not experienced before. While his love for Elizabeth is very powerful, it is just one emotion among many, and when Elizabeth is taken by the dybbuks, he is at the mercy of other volatile feelings like anger and vengeance, putting lives at stake.
Griffin, Celia, and Even must not only track down Elizabeth, they must also stop Lev from becoming a human time bomb.