"Former US Air Force officer Nick Flynn joined the clandestine Quartet Directorate to continue its long-standing mission: to act decisively against serious threats to the free world. And with the backing of Russia's authoritarian president, no threat is more deadly than that of Pavel Voronin and his mercenary Raven Syndicate. Twice they have almost succeeded in bringing the United States to its knees, only to be stopped at the last moment by Flynn...