From January 1935, this is still one of my favorites in the series and a great example of classic Doc Savage. There's a weird menace and mysterious murders on a foggy rainy night in New York City...and then, in a medieval fortress city near Tibet, there's more action and intrigue, culminating in a full scale uprising. If you wanted to introduce a fan of high adventure fiction to Doc Savage, THE MYSTIC MULLAH would be a good choice.
Of the dozen or so great villains Lester Dent came up with, I'd include the Mystic Mullah on the list. Here's a supernatural creature that has existed for a million years, appearing as a luminous green face floating in mid-air. The souls of his many victims become his green slaves...drifting, nebulous snake-like things that burn people cruelly with their touch and which can kill by making a person's neck snap suddenly. (A cheap cartoon version of these creepy things was used in the George Pal movie.)
A tense moment occurs when Doc first sees the green soul slaves and peers at them so inquisitively that he doesn't see them surround him. Nothing he tries helps evade them and he knows their touch is fatal. "The bronze man was breathing heavily now. It was one of the few times in his life that he had been trapped with no avenue of escape at hand."
Dent does a good job here presenting the puzzle of who is really behind the Mystic Mullah. Joan Lyndell, wealthy European who owns much of the city Tanan? The grim warlord Khan Nadir Shar? Oscar Gibson, a insolent Texan working for the Soviet government? Mihafi, the bald commander of the rebellious army? The narrative is really careful here and suspicion falls plausibly on each one.
The gadgets are varied this time. Doc has time bombs which spray tiny bits of his anesthetic in crystal form, a dazzling magnesium flare powder in his heel, and a thermite compound in the lining of his tie (harmless unless mixed with the buttons of his coat). He also has an armored speedboat with "so much engine that it seemed on the point of sinking whenever it was not in motion."
While Monk and Ham dominate the action, the other aides get some attention. We meet Johnny in the lab on the 86th floor, wearing a rubber apron and gloves as he is assembling the vertebrae of a small dinosaur. Renny takes part in much of the action and is hardboiled enough to keep going after a bullet makes "a rather gory mess of his left ear." (Luckily he has a friend who is the world's best plastic surgeon, eh?) Long Tom doesn't get to do much fighting, but it's interesting that he understands one of Johnny's sentences and sourly gives the gist of it to Renny.
The second part of the story takes place in Tanan, a walled city near Tibet with a very barbaric population. The men all wear swords and seem to live on bandit raids into the hill tribes. The Mystic Mullah has half the population under his control, including most of the army,and the violent overthrow of the Khan Nadir Shar seems imminent. Dent provides a convincing atmosphere of suspense as Doc and his team arrive. The city is ready to explode into mass slaughter.
One gruesome touch is that the Mystic Mullah has ordered the bodies of his victims left in the streets on piles of rock, to demoralize and intimidate the people. Actually, this wasn't an unknown practice in an era when heads were stuck on poles at city gates.
After reading some of the later novels, which portray Doc as having nervous moments and periods of cold sweat (not to mention a complete breakdown after THE DERELICT OF SKULL SHOAL), it's interesting to note that here in 1935, at his most invincible, he's still a human being and not a fearless fighting machine. I mentioned the scene where he's caught by the soul slaves. And when the bronze man is surrounded and captured by a group of heavily armed bandits, but has no signs of fear on his calm face, one of the Tananese says that a wise man knows when to be frightened. Doc replies (in their own language) "There can be fear without shaking and wailing." I'm finding several references in the early adventures to the effect that Doc is brave but not without normal prudence.
It's been mentioned many times from 1933 to 1949 that Doc gets as big a kick out of the danger and mayhem as his friends do (although he doesn't like to admit it). If he really had unlimited nerve and wasn't affected by the perils, he wouldn't enjoy them. Natural adrenalin is his addiction.
Finally, the Bantam cover by James Bama, in a lovely two tones of green, shows a beautifully rendered floating head of the wizened Mullah himself, glaring down at Doc. Our boy has grenades in both hands and is ready to throw one at the scowling face (he's obviously not intimidated). This was one of the first Bantam covers Bama did,and he shows Doc in the loose robes of Tanan, with a curved short sword across his waist.
Later, of course, the Man of Bronze was invariably shown in the torn shirt, riding pants and boots, whether appropriate or not. It was his superhero costume in that sense, as easy to recognize on the bookstand as a blue shirt with a big red S. It may have made sense to have portrayed Doc in the outfits he was wearing in the stories but that vivid Bama image caught the eyes of many readers for decades and kept the reprints coming.