Mortal Causes is the sixth novel in the Inspector Rebus series, written by internationally acclaimed author Ian Rankin. The story takes place in August in Edinburgh, during the height of the festival. Amidst the festive atmosphere, a brutally mutilated body is discovered in the city's ancient underground streets. The distinctive features of the body lead Inspector Rebus to suspect a possible connection to sectarian activists. The idea of a terrorist attack in a city flooded with tourists seems almost unimaginable. When it turns out that the victim is the son of a notorious gangster, Rebus realizes that he is on the brink of chaos that is about to erupt.