Sabriel

Garth Nix's fantasy novel opens his Old Kingdom series. Sabriel has lived south of the Wall since early childhood and attends a girls' boarding school in Ancelstierre, a country whose government officially denies the magic of the Old Kingdom to the north, where the Dead do not always stay dead. Her father, the Abhorsen, is a necromancer whose task is to put the Dead to rest. When an undead messenger reaches her school carrying his bells and sword, Sabriel learns that he has been sent beyond the Seventh Gate of Death, and she must cross into the Old Kingdom to find him. Later books in the series include Lirael and Abhorsen.

Brandon Sanderson called Garth Nix wonderful and suggested Sabriel to anyone who has not tried it.