Behind Edinburgh's regimented Georgian facades, its moral compasses are spinning with greed, dishonesty, lust and murderous intent. Isabel Dalhousie knows this. Isobel, in fact, rather relishes it. An accomplished philosopher and editor of the Review of Applied Ethics, she knows all about the difference between good and bad. Which is probably why, by instinct, she is an amateur sleuth. And instinct tells her the man who tumbled to his death in front of her eyes after a concert in the Usher Hall didn't fall. He was pushed...