Fletch

Probably because Chevy Chase gave it a bad name, Gregory Mcdonald's Fletch series (featuring Private Investigator Irwin Fletcher) seems to be almost entirely forgotten today. Which is a shame since Fletch, the first book in the series, has an uncommonly intelligent and cohesive plot, as well as sharp and often very funny dialogue. (Oddly, while this was the first Fletch book published, it is the fourth in the chronology, a confusion that probably further contributed to its obscurity.)