I've been hearing about this book for a few years now and it has sat on my kindle for some time. I'm glad I finally picked it up to read it.
The story is about Sabriel, who is from some magicalish kingdom which shares a border with what I think is our world. She is the daughter of the Abhorsen who is a sort of necromancer in their world. Her mother dies at birth and she would as well if he didn't go after her and bring her back dealing with an old enemy while doing it. She grows up in the regular world, though at a school which knows about and teaches magic.
After her father doesn't show up for their nightly chat and she is sent his magical bells and sword she realizes that he has been captured or killed. She chooses to go with captured and is determined to save him. She hasn't been in their world since she was five but manages to figure out where to go and gains allies.
It's a really interesting and inventive book, though as you can probably tell I'm still a bit confused on the world. I have also heard good things about the audiobook series so I may actually try switch to that :)