Not your everyday WWII spy novel, and by no means perfect, but a sufficiently gratifying pick from the Kindle First heap and a relatively quick read.
As for genre, this seems to be a mash-up between historical fiction, a garden variety page-turning spy novel, and ... something else, but I'm not sure what. On one level, the novel chronicles - and, apparently, takes any number of liberties with - the career of a (subsequently) celebrated spy, an actual historical figure, of whom there, apparently, was a rather definitive biography written in 2003 (in French), later translated into German (2004) and English (2004 or 2005), A Spy at the Heart of the Third Reich: The Extraordinary Story of Fritz Kolbe, America's Most Important Spy in World War II. Having not read the non-fiction version - which one must assume is more factually accurate but also more dry than this story - it's impossible to compare. Frankly, I wish I'd read the biography first so that I could compare them; but, having read this, I don't see myself rushing out to read another 300 pages on the same topic (particularly now that I spent some time doing online research and figuring out what portions of the story do and don't align with the mostly widely accepted historical record)...
Of course, we're reading a translation, so I'm in no position to fully apportion my (mostly minor) frustrations with the book between the author and the translator. There's no question that it's a compelling story, and any life, let alone such a life, at such a time and place, must have its share of joys and sorrows. My gripe with the author is that I didn't find two of the major artistic decisions worth the candle. The temporal ping-pong between the retelling and the action story didn't seem worth it (to me) in light of the minimal pay-off at the end; nor did the introduction of a reporter and a photographer (two additional voices that, again, to me, felt like interlopers) add much to the suspense, texture or overall presentation. (OK, introducing romantic tension between characters unrelated to the historical story line had me scratching my head, particularly since we learn that the definitive biography of Kolbe was written long after his death.) Other than that, I wasn't inspired by the prose, and I found the vocabulary inconsistent and, in spots, disappointing. But these are mostly quibbles that kept an enjoyable, entertaining, informative, page-turning read from being something really special.