City of Bones by Cassandra Clare

While Clary and her friend Simon are at a club, she witnesses three teenagers murder another teen. Stranger than the odd tattoos that cover their skin or the weapons that they use is the fact that the body disappears into thin air. Stranger still is the fact that no one can see them except for her. Clary is immediately taken into the world of the Shadowhunters, part human/part angels who rid the Earth of demons. When Clary returns home, she finds that her mother has been taken by demons. Clary must then rely on the Shadowhunters, in particular the handsome but snarky Jace, to help her uncover the mysteries of her past so that she can save her mother.

With many characters and subplots, this story is extremely action packed. Between battles, there are friendships and potential love connections being made. One of my new favorites!