An American agent crashes into the display window of the GUM department store in Moscow. His dead body is full of poison, and his briefcase contains every secret of value to Russian Intelligence, typed out on paper from the American embassy. Worse, some of the information has also turned up in secret files in Peking. In order to discover the leak and the people behind it, the Russians demand American aid, accusing them of the leak.
Enter Nick Carter, disguised as Mark Slade, minor agent, disguised as Ivan Kokoschka, novelist. After many near misses, he discovers the Brothers Twelve, a ring of Chinese agents, using a miniaturized light-activated listening device literally drawn onto a painting, to gather secrets.