Le Blues du tueur à gages (Pocket Book)

Hit Parade features characters with shades of gray, and I'm curious what motivated the author to explore moral ambiguity in this way.

The story hit a lull before picking up again, and I wonder if that was intentional to build tension or just the natural flow.

The ending caught me off guard but felt earned. I'm interested in what clues or hints were woven in earlier that I might have missed.