Terrier: Beka Cooper, Book 1 (by Tamora Pierce)

Beka has grown up in the slums of the Lower City in Corus, the capital of Tortall. When she was 8, she helped the Lord Provost capture a gang of thieves, and he took her and her family under his wing. Now she's 16 and training to be one of the police guards (called Dogs) of the city. As a trainee (Puppy), she's assigned to the best Dogs in the Kennel, though they're reluctant to have her. But soon, through her unusual ability to hear the voices of the dead, she gets wind of two serial murderers: one hiring and then killing groups of men, the other kidnapping and murdering children. As she and her Dogs work to track down the murderers, gradually she earns their respect through her tenacity, which wins her the nickname "Terrier."

Told by main character Beka through journal entries, this unusual combination of fantasy novel and police procedural is very satisfying. TERRIER is a rip-roaring good story with unusual elements, set in a world that author Tamora Pierce has been developing for decades. It makes a good introduction to Pierce's work for those who haven't read the earlier books.
 

Beka is a delightful heroine: painfully shy, modest yet exceptionally competent, eager to learn, and strongly empathetic toward the downtrodden people she grew up with. Pierce has made her reputation as a writer with strong heroines, which has turned her into a darling of those with feminist leanings. But it would be a mistake to pigeonhole her as a feminist author -- she's simply too good. Though boys are notorious for rejecting books with female protagonists, if they allow themselves to try this, they'll like it as much as Pierce's female fans will.