Grudge Count - Jon Latham - Bog

Willow Sturgeon is a patrolman that learne on ending her shift one day, that she is being promoted to detective. She learns the promotion is a numbers game, as the department has no female detectives. She also learns she is being partnered with the department drunk. Something she's not too fond of due to a previous family experience with an alcoholic.
Travis Birch is the departments best detective. However, Travis' talents are declining. He has become slow to react and constantly smells of alcohol. The captain has one chance to save him, before putting him on administrative leave. Willow Sturgeon.
As the captain hoped would happen, Willow tears into Birch from minute one and doesn't let up the entire shift. Birch retaliates, but his attempts to demean her fail.
The two are assigned to a case of a woman's body found in a city park. Stabbed six times. During their subsequent investigation of the scene, they uncover a second body. Stabbed five times.
On the second day, Willow finds herself basically alone and she continues to dig into clues, including a picture found in one of the victim's apartment.