This second novel of the Secret Generations trilogy is much less of a family saga and history of the birth and developments of the intelligence services (which was the case for the first book) and more of a classic spy thriller; still a pretty good one...
The story takes place, with some back and forth in time, between the preWWII and the immediate post war periods; only a few of the large Railton family featured in book one play a major role here (though many others appear in the background), and the storytelling is much more singleminded. This is essentially the story of a network of the French resistance during WWII, and of the several double and triple games played by their members and the numerous connected players (the SIS/MI6, the OSS/CIA, the NKDV/KGB, the Abwehr).
Don't get mistaken by the fact that the author has been the James Bond novelist for the last decades: the style here is much more Len Deighton (or even to a lesser extent Le Carré) than 007. The plot is quite complex and articulated without being overworked, the key characters are all 3D and quite engaging, the connections between fiction and history rather interesting.
So, very enjoyable read and already looking forward to the third and last book of the series.