Today, I finished re-reading The Dain Curse by Dashiell Hammett, one of his six novels, and one of two to feature his nameless detective - the "Continental Op".

I've always admired The Dain Curse for it's twisted plot, as the Continental Op starts out investigating a simple diamond theft and then gets pulled into family mysteries and a number of murders. It's not as good as the first, and much, much bloodier and hard-boiled, Continental Op book Red Harvest, but if you want to see the start of the modern private detective genre, you can't go wrong with Hammett.