Long before I began to work seriously on Finch, my latest novel, I had fragments of something called, er, Fragments From a Drowned City, which was about a detective who comes to Ambergris seeking a girl apparently abducted and brought to the city. (I worked on it from 1999 to 2001.) It never really came together because I couldn’t at that time imagine the city of Ambergris with the subterranean gray caps in control. I also didn’t really know what happened to the detective. However, in reviewing