February’s book for discussion, The Bookseller by Mark Pryor, is the first in the Hugo Marston series.
Max—an elderly Paris bookstall owner—is abducted at gunpoint. His friend, Hugo Marston, head of security at the US embassy, looks on helplessly, powerless to do anything to stop the kidnapper. Marston launches a search, enlisting the help of semiretired CIA agent Tom Green. Their investigation reveals that Max was a Holocaust survivor and later became a Nazi hunter. Is his disappearance somehow tied to his grim history, or even to the mysterious old books he sold?
Description from Goodreads https://www.goodreads.com/book/show/15795957-the-bookseller?ac=1&from_search=true&qid=9Zgzt4RUq5&rank=2