Captain Wiggins wrote a book about Lieutenant Polk and his involvement in a Grendel caper. It is unknown whether this story is real or if Wiggins made it up.
Polk is a down-to-earth, divorced cop who accidentally hears his captain taking a bribe. He investigates and gets extremely involved in figuring out a complex scheme involving a seeming take-over of the city's diamond markets. It centers on the Wiesburg diamond company. However, it then turns out that it is also a scheme to cut Grendel out of his normal share in the illegal profits. Polk is smart, honest, and dogged, and keeps investigating. He eventually figures out that Esther Wiesburg has manipulated her father Ed's will so that she and her brother Ray will get all his money.
His friend Pynchon tells the police all the details, and Polk has to spend an afternoon explaining it all to Argent. Argent takes him off the case, but Polk won't let it go.
He shows up at the big dinner where the scheme will take place. He confronts Esther, but Grendel is also there, and he disarms Polk. Esther grabs his gun and kills Polk.