The list author says: "Here are all of the Mitch Rapp books. Their place in the series is denoted in the comment field. You should read the books in this order to gain full understanding of the continuous plot line and characters that Flynn uses."
"#0 - Mitch Rapp is not in this book but many important characters from the "Rapp" series of books appear here. It is DEFINITELY worth reading and I suggest you do so before you start the Rapp series... although it certainly isn't a requisite for understanding the others."