Out of the teeming turbulent East had come Dr. Yen Sin-saff-ron-skinned wizard of crime-bringing to the capital of the West all the ancient Devil's-lore at his command-and a horde of Asian Hell-born to help him spawn it. But Michael Traile-The Man Who Never Slept-had crammed into his own keen brain the means to cope with the sinister doctor. For he knew even the secrets of the Dragon's Shadow and how to penetrate the yellow murder fog that had descended on the capital to mingle its blood-wisps with the mist from the Potomac.