Christmas Eve in Boston is no holy night for medical examiner Dr Maura Isles. In a rundown house a woman has been dismembered in an act of carnage that leaves veteran cops in shock. The last person called from the dead girl's phone is Dr Joyce O'Donnell, a celebrity psychiatrist who's made her name defending serial murderers. But there are other clues that make the police wonder if this slaying was part of a Satanic ritual. Drawn on the wall, in blood, are ancient symbols, and a mirror-image word in Latin that, translated, says: I have sinned. Then a second woman is found butchered on Beacon Hill, just outside the grand residence of Anthony Sansone, a reclusive historian. He is the leader of