Lirael introduces an entire new set of characters. The stars of Sabriel play only minor role in this book. This is book focuses on Lirael, a young teenager growing up with the Clayr. The Clayr are a community that possess the "sight" - they can see into the future. Typically, this ability to see into the future arrives around age 12 or 13. But Lirael is already the oldest girl in the community who lacks the "seeing" ability, and the birthdays keep ticking past. The Clayr and Lirael realize that the seeing is not for her, and so she is sent to work as a 3rd assistant librarian.
I love the library that Lirael roams. It is big and scary, with plenty of dangerous areas protected by spells and full of lost treasures. Lirael is a lonely sole, speaking little to the other librarians, prefering to lose herself in the work of librarian, and exploring in her spare time. She is not entirely alone - Lirael is befriended by a talking dog (the dog has the unlikely name of Disreputable Dog).
The story of Sameth, a young prince of the Old Kingdom (and son of Sabriel and Touchstone) alternates with the sections about Lirael. Sameth was studying on the other side of the wall (where magic doesn't work) when he and a busload of his classmates are attacked by a undead zombies controlled by an evil necromancer named Hedge. Sameth thwarts the attack, but finds himself recalled to his home in the Old Kingdom. It seems there is trouble everywhere, and Sam must begin his training as Abhorsen-in-Waiting (Sabriel currently holds the title, but times are dangerous, and she has been wounded in recent desperate battles with the undead.) Sam does not want to be an Abhorsen. His gift is working Charter Magic, not commanding the undead. He decides to runaway.Meanwhile, the Clayr have gathered (assembling in a group allows them to see further and clearer into the future) and seen a vision of Lirael in the future helping a young man on a lake. The Clayr decide that Lirael must be sent to that distant lake, because her presence may stop the mysterious evil power that has been tormenting the Old Kingdom. Of course, Sam and Lirael are destined to meet.
Unlike the first book in this series, Sabriel, which was a self contained story, Lirael is only the first half of a bigger story. The conclusion is in Abhorsen. I enjoyed the first two books, so Abhorsen was immediately checked out of the library.