THE SHADOW'S SHADOW, first published in February, 1933, was the 23rd adventure of the Master of Darkness. I finished reading the Pyramid Books reprint (from July, 1977) the other evening and it's another corker.
Master villain and international criminal Felix Zubian and wealthy man-about-town Douglas Carleton, plot to steal millions in diamonds. They know the only thing standing against them is The Shadow so they decide to take the fight to mysterious crime-fighter. Zubian and Carleton are aided in their fight against The Shadow by tough talking gangster Gats Hackett who refers to his two huge revolvers as "smoke wagons". Only in the pulps! The villains discover and capture two of The Shadow's agents, Harry Vincent and Rutledge Mann and through careful observation, deduce that The Shadow is really Lamont Cranston.
But The Shadow is, as always, a step ahead of the crooks He ditches the Cranston persona and becomes Henry Arnaud. There are several gun battles (with high body counts) before the final showdown in which all of the villains are slain and Zubian, before he dies, catches a glimpse of The Shadow's real face, which is neither Cranston nor Arnaud. What is the true face of The Shadow? Author Walter Gibson's not telling.
With a terrific cover by the legendary Jim Steranko, THE SHADOW'S SHADOW is pure pulp pleasure. Recommended.