When an scorpion relic is discovered in an ancient tomb, a man is given the ability to turn into a superhero to prevent its use for evil purposes.
This serial is often considered one of the best ones ever made, and I think it earns its plaudits. I think it may be the only time that Republic actually gave its central hero super powers rather than just a cool costume, and it has an interesting effect in that it cuts down on the lengthy fight scenes; when the hero can dispatch the villains with a single punch, it has a way of streamlining the fights. It also does a number of things right; the comic relief character, though he plays a major part in the proceedings, is used for comic purposes only sparingly, and he totally avoids being annoying. The Scorpion is a very effective villain, each episode is very well done and makes good use of Captain Marvel's powers, and it avoids lame cliffhangers. This serial manages to be equally fun throughout its length; it may be the only time when, after watching the final episode, that I wished it had gone on for a few more.