The Gray Man novels are typically published in a certain sequence. However, without more specific information, it's hard to list the exact order. Generally, they follow the chronology of the story development within the series.
Well, 'On Target' is also a great 'Gray Man' novel. It continues the story of the main character with more complex missions and deeper character development. The story unfolds in a way that keeps you on the edge of your seat, with lots of twists and turns.
The Gray Man in Spenser novels is often a mysterious figure. He might be a character with a complex backstory that is gradually revealed throughout the narrative. He could be an antagonist, or perhaps a morally ambiguous figure who adds depth and intrigue to the story.
The gray man is often described as having a hazy or shadowy appearance, like a figure made of mist. He is usually associated with a feeling of coldness.
One of the main themes is espionage and the shadowy world of international intelligence. It often deals with the idea of a lone operative, like the Gray Man, navigating dangerous and complex situations.
Action and adventure are major themes. The Gray Man is constantly on the run, facing various dangerous situations and enemies, which makes for a lot of exciting chase and combat scenes.