The body of a man is found hanging in an empty house. To the Edinburgh police force, this is a simple suicide case. But something about the scene strikes Detective Inspector Tony McLean as being off. Days later another body is found hanging from an identical rope, with a noose tied in the identical way. McLean is convinced that these people are either being murdered or somehow coerced into taking their own lives. Then a third body is found.

Under pressure from his superiors to wrap the case up quickly and neatly, McLean must also deal with the fallout of his last big investigation--not to mention the difficult trials of his personal life. But the deeper McLean digs, the more he comes to believe that something evil is stalking Edinburgh's streets. He just hopes he can stop it before someone else succumbs to the hangman's song.