The Devil's Star — Jo Nesbo

In the heat of a sweltering Oslo summer, a young woman is found murdered in her flat--with one of her fingers cut off and a tiny red star-shaped diamond placed under her eyelid. An off-the-rails alcoholic barely holding on to his job, Detective Harry Hole is assigned the case with Tom Waaler, a hated colleague whom Harry believes is responsible for the murder of his partner. When another woman is reported missing five days later, and her severed finger turns up adorned with a red star-shaped diamond ring, Harry fears a serial killer is at work. But Hole's determination to capture a fiend and to expose Waaler's crimes is leading him into shadowy places where both investigations merge in unexpected ways, forcing him to make difficult decisions about a future he may not live to see.