A Tap On The Window by Linwood Barclay

A very good mystery by a Canadian author (chosen from the CBC List of 100 Authors who make us proud to be a Canadian).  This is a plot-driven mystery, so not much description of place. An intrepid private eye solves several murders, with the usual corrupt police force. There is a good surprise at the ending!

https://www.goodreads.com/book/show/16072980-a-tap-on-the-window16072980