Ruth Rendell is bidding fair to join Defoe and Dickens in creating one of the great criminal cities of literature. Her view of London is a similar murderous topography, less squalid, but with the same tentacles reaching out between rich and poor. The mapping of this novel began over a decade ago with the publication of her A Sight for Sore Eyes, which featured "Orcadia Cottage", a charming old house in St. John's Wood painted by a well-known artist as a backdrop for his portraits of a devoted young couple.