“Double Agent” is the second in a spy thriller series with blancmange titles (the first was called “Secret Service“) that is very ambitious, Le-Carre-level ambitious. Starring MI6 spy Kate Henderson, whose entire family and circle of friends seem to be involved in the secret world, the series involves convoluted mazes of treachery and high geopolitical drama. Kate is kidnapped in “Double Agent” in order to be offered a high-level defection that claims to bring proof that the British Prime Minister is a spy. The plot sweeps from London to classic spy locations such as Berlin and across the Russian border, the storyline is paced fast and tightly. Kate herself is an engaging espionage hero, seemingly brave and talented, yet wracked by insomnia and tension (I won’t spoil a key plot element, but she should be anxious, a result of the first book’s betrayals). Tom Bradby, a TV anchor and documentary maker, is a smooth stylist who comes close to showcasing the secret world’s depth and ambiguity. I read the first three quarters in a rush of adrenaline, then had to blink while the finale’s gymnastic plot gyrations overwhelmed the book’s characters and themes. If I turned the last page with a slight sense of letdown, I’m hanging out for the next volume, and what more can one ask for from a spy thriller?