For the most part, I'm choosing popular and fairly well-known authors. However, now and then, I'm going to highlight one of my personal favorites who probably isn't as well known, even to fans of the genre. Greenleaf wrote the John Marshall Tanner series of mysteries set in San Francisco. I'm not really sure why I like these so much, but they are well-written with interesting plots and characters. The characters, especially Tanner, really grow over the course of the 14 books. These books aren't always easy to find (my collection was stolen and I am trying to rebuild it) but they are worth seeking out. This is a series where it's important to start at the beginning with Grave Error.
Book: Gone, Baby, Gone by Dennis Lehane / Gone Girl by Gillian Flynn
I just couldn't choose between these two for my "G" books and they do have the same word in the title, so I'm picking both. Each of these explore the dark side of humanity, and are not easy reads. Gone, Baby, Gone in particular, with its depictions of horrific child abuse, is incredibly hard to get through, but the payoff is worth it. In Gone Girl, the author shows the reader how a marriage can go horribly wrong. Both books also have twists that I won't reveal in case you haven't read them yet - and I recommend you do so immediately. (Gone, Baby, Gone is part of a series, but it also works as a stand-alone novel.)