The silent sisters

After a harrowing escape from Russian agents on his last mission, Charles Jenkins thinks he's finally done with the spy game. But then the final two of the seven sisters--American assets who have been deep undercover in Russia for decades--cut off all communication with their handlers. Are they in hiding after detecting surveillance? Or have they turned and become double agents? It's Jenkins's duty to find out, but he's been added to a Russian kill list. It will require all of Jenkins's knowledge of spycraft--and an array of disguises--to return to the country undetected.