Bob Moats has written a very entertaining series about a "senior citizen" private investigator wanna-be.  There is a fun cast of characters (and I do mean characters), very interesting mystery that has enough twists and turns to make it interesting, and murder with a side or two of humor to liven up the mix.  Don't want to give too much away so I will just say that this is great entertainment and you won't want to put the book down.