Michelle Chouinard led a number of us mystery writers on an eye-opening walk of San Francisco’s Jackson Square area. We learned that we were walking atop land fill studded with dozens of buried wooden sailing ships. Chouinard told chilling, sometimes crazy tales of murder and mayhem, shanghaies and scams. Her mystery series, A Serial Killer Guide to San Francisco, covers some of the same ground. The latest, A Map to Murder, focuses on Haight-Ashbury.