I believe this is one of Harris' earlier forays into mystery fiction. While not a bad story and not bad writing, there were some unexplained jumps in action or logic.

The main character tended toward - what? whining? maybe not that - there was a lot of "I've got to get ahold of myself", especially toward the beginning of the book. Whodunit and why was one of those "never in a million years" things - the clues (for me) just weren't there until right before the big reveal. Oh, and then after the big reveal? The End. No denoument, no further explanation, no happily ever after (or not). Just DONE.

Having said all this, I finished it, I didn't consider abandoning it. The book kept my attention and didn't make me crazy.