The story takes place mostly in Barcelona during 1936-39 Spanish Civil War. The Nationalists led by General Franco and backed by Germany and Italy were trying to re-take the country from the Republicans which were comprised of a number of left wing groups from anarchists to Stalinists. The main characters are Robert Florry and Julian Raines, two Eton school chums who have fallen out but have both joined the International Brigade. Raines is thought by MI-6 to be a Russian spy and Florry is sent to Spain to kill him. Two other key people are Sylvia, a beautiful young British adventurer and Levitsky, a Trotskyite spymaster and chess champion. The main villain is an American ex-hitman who has become an enforcer for the Stalinists under an assumed name.

There are many twists and turns, sometimes confusing but almost always interesting. Things get sorted out in the end, of course, with even more surprises.

The further I got into the story the more I enjoyed it to the point I found it difficult to put the book down. I recommend it as both a good spy story but also as a well done piece of historical fiction.