4?/series. Dutch Inspector Van Veeteren again tackles a mysterious killer who simply knocks on doors and shoots the man who answers. Or is it that cut-and-dried? Two chest shots followed by two to the groin? Sounds a little personal. Digging into the victim’s past lives as the body count rises, Van Veeteren finds a link but can’t figure out what it means. But the future victims know, and take steps to neutralize the killer. Read it, you’ll love it. A four.