James McGregor gets hired to investigate a sunken yacht. Only he finds out that the yacht hasn't been sunken yet and everyone is lying to him. Throw in diamond smuggling and hammerhead sharks and that's pretty much it.
Grave Descend is a lighting quick read, full of action and intrigue, just what you'd expect from a Hard Case read. But it's a little too breezy. The print is larger than any Hard Case I've yet encountered and it was probably about 150 pages long when it was first published.
John Lange, aka Michael Crichton of Jurassic Park fame, writes a pretty passable detective story.