Sabriel

In the Old Kingdom, there is still magic.  There are charter mages who can use that power to build or to destroy.  There are necromancers who can travel in death; sometimes they don't come back alone.

Sabriel's father is the Abhorsen.  He is a type of necromancer but not one who works with the charter.  Long ago the charter made order out of chaos and bound many of the free magic creatures who would consume and destroy.  While other necromancers work against the charter to bring the dead back into life for their own power and purposes, the Abhorsen makes sure the dead stay dead.

Sabriel is away at school beyond the wall that separates the Old Kingdom from the modern world.  When she gets the message that her father is missing, she must travel back to the Old Kingdom to Abhorsen's house to discover what has happened to her father and to try and save him.

But there is more to this story than simply a missing father or even a missing Abhorsen.  An evil more than 200 years old is awakening, and his goal is to destroy.  With the help of Moggett, a creature who takes the shape of cat, but is certainly no ordinary feline and Touchstone, a swordsman and charter mage with his own secret past, Sabriel will not only have to complete her quest, but she will have to accept her destiny for good or ill.

I first read this series over 10 years ago, and I recently decided to reread the whole trilogy as Garth Nix is adding more titles to the Old Kingdom world.  I cannot recommend them highly enough for fans of dark complex fantasy.  I still enjoyed the entire series as much today as I did the first time.