Therapy (Alex Delaware #18) by Jonathan Kellerman

“Been a while since I had me a nice little whodunit,” homicide detective Milo Sturgis tells Alex Delaware. But there’s definitely nothing nice about the brutal tableau behind the yellow crime-scene tape. On a lonely lover’s lane in the hills of Los Angeles, a young couple lies murdered in a car.

Each bears a single gunshot wound to the head. The female victim has also been impaled by a metal spike. And that savage stroke of psychopathic fury tells Milo this case will call for more than standard police procedure. As he explains to Delaware, “Now we’re veering into your territory.”