Abhorsen is the third in a trilogy, and takes its name from a mystical profession whose "birthright and charge [is] to maintain the borders of Life and Death." This finale to the series starts off explosively, with an assassination attempt on King Touchstone and Abhorsen Sabriel -- familiar characters from the earlier novels -- who are on an embassy to the city of Ancelstierre.

On the other side of the wall, in the Old Kingdom, Lirael -- once a Second Assistant Librarian of the Clayr and now an Abhorsen-in-Waiting -- finds herself, her nephew Prince Sameth and a group of her friends caught in a sorcerous trap by Chlorr of the Mask, the ally of an evil necromancer named Hedge. Hedge has a plan in motion to use Sameth's old friend, Nicholas Sayre, to unearth a creature called Orannis the Destroyer to lead an army of the dead in the annihilation of all life. It's up to Lirael and her friends to break out and rescue the ensorcelled Nicholas; when that fails, they're forced to fly to Hedge's first target, Ancelstierre, in the desperate hopes of finding a way to forestall Orannis' horde and defeat him. Finally, with the help of Sabriel and Tochstone — who arrive on the scene after narrowly escaping their assassins — Lirael is able to fashion a way of warding off Orannis' power, and with the help (and ultimately, the sacrifice) of her friend Diresputable Dog, she is able to contain the Destroyer, save the world and rescue Nicholas Sayre.