As well as its advantages, there are drawbacks to the enlightened village that is twenty-first-century Edinburgh, where every Saturday night ears burn at dinner parties across the city, and anyone requiring the investigative abilities of a philosophical soul knows where to find her. Jillian McKinlay - wife of a trustee of an illustrious school - is the latest petitioner; she asks Isabel to look into a poison-pen letter that makes insinuations about applicants for the position of principal. Isab