Now & Then by Robert B. Parker
I've actually read this book before, but I'm about out of reading material.
The story of Spenser, private eye, and his investigation into the murder of one of his clients. A pretty good read, though I must say, after reading every one of Parker's books, I'm getting a little sick of the banter between Spenser and his girlfriend.
But, if you're new to him, and are a fan of detective novels, you will probably find this interesting.