As detailed at Pulp Super-Fan, Doc debuted as a backup in the Shadow’s comic in 1940, then shifted to his own book. The book didn’t feature Doc alone but also Ajax the Sun Man, Mark Mallory, Captain Fury and other characters. During this period, the stories were adapted from the pulp novels, such as The Red Serpent based on The Crimson Serpent and The Polar Treasure based on the same-name novel.
I thought Marvel had problems squeezing the plot of a pulp into two regular issues, but the eight-pagers from this era are even worse. Doc’s supporting cast are trimmed down and the Polar Treasure adaptation begins with Doc and Victor Vail already in the Arctic (the opening page narration sums up what has gone before).
In 1941, things changed. Doc crashed in Tibet and like countless Westerners before him, encountered Tibetan mystics who could endow him with great powers, via a magic ruby. This new, super-powered Doc Savage (also used in a Street & Smith radio show) ran until the comic was cancelled and Doc moved back to The Shadow in 1944. Unfortunately I haven’t found any stories from this era online.
After a couple of issues Doc ditched the ruby reverted back to a straight crimefighter.In 1948’s Television Peril, a scientist ignores Doc’s warning that matter transmission by television (yes, it’s the same thing as teleportation, but TV was cool and new back then) and becomes the dupe of a schemer who plans to send armies instantly across the globe for conquest. It’s not an adaptation but it’s not far off Doc’s regular adventures. The Crystal Creatures, in which research into plastics creates unkillable silicon monsters, is closer to an issue of DC’s Strange Adventures in tone.
And that’s pretty much all I have on this period, but I’m grateful for the various sites that put this material up online. I have now read at least something from every era of Doc Savage comics — at least until the next comics publisher gives it a shot.