I should also mention the writing style—if it's known for being fast-paced, descriptive, or having a particular narrative technique. Since it's the 12th book, maybe the detective has evolved a bit, or there are references to past cases.
Potential for analysis: The symbolism in the five-hour timeframe—could represent a limited time to solve the case, a countdown, or a period of intense investigation. The psychological impact on the detective character and how this case affects him differently than others.
Themes to discuss: the exploration of time and how the five-hour window is pivotal, the psychology of the perpetrator, the impact of media or public perception if that's a factor. The use of suspense and pacing in a 5-hour framework might create tension.