Captain America is a 1944 Republic black-and-white serial film loosely based on the Timely Comics (today known as Marvel Comics) character Captain America. It was the last Republic serial made about a superhero. It also has the distinction of being the most expensive serial that Republic ever made. It also stands as the first theatrical release connected to a Marvel character; the next theatrical release featuring a Marvel hero would not occur for more than 40 years. It was also the last live-action rendition of a Marvel character in any media until Spider-Man appeared in the Spidey Super Stories segment of the children’s TV series The Electric Company in 1974.

The serial sees Captain America, really District Attorney Grant Gardner, trying to thwart the plans of The Scarab, really museum curator Dr. Cyrus Maldor – especially regarding his attempts to acquire the “Dynamic Vibrator” and “Electronic Firebolt”, devices that could be used as super-weapons.

In a rare plot element for Republic, the secret identity of the villain is known to the audience from the beginning, but not to the characters in the serial. The studio’s usual approach was the use of a mystery villain who was unmasked as one of the other supporting characters only in the final chapter.

Plot
A rash of suspicious suicides among scientists and businessmen, all found holding a small scarab, gets the attention of Mayor Randolph. He demands that Police Commissioner Dryden and District Attorney Grant Gardner get to the bottom of the case, while openly wishing that Captain America, a masked man who has helped defeat crime in the past, were around to solve the mystery. Gail Richards, Grant Gardner’s secretary, investigates and realizes someone knows of the “Purple Death”, a hypnotic chemical responsible for the suicides. However he then pulls out a gun and takes her into another room. He then orders an associate to tie her up. The D.A. realizes she is there and forces the man to take him to her. He finds her tied up and gagged. He frees her but it is threatened that the purple death will be dropped killing them all. But the D.A. shoots him then gets out of the room with Gail.

All of the suicides were members of an expedition to some Mayan ruins. One of the few remaining survivors, Professor Lyman, turns to his friend Dr. Maldor for support. Dr. Maldor, however, reveals that he is the man responsible for the deaths. He wants revenge because he planned and organized the expedition but everyone else claimed the fame and fortune. However, Lyman has developed the “Dynamic Vibrator” – a device intended for mining operations but one that can be amplified into a devastating weapon. Using his purple death Dr. Maldor forces Lyman to disclose the location of his plans.

Captain America intervenes as the Scarab’s heavies attempt to steal the plans and this leads to a sequence of plots by the Scarab to acquire a working version, as well as other devices, while trying to eliminate the interfering Captain before he succeeds in discovering Dr. Maldor’s true identity or defeats him.

Cast
Dick Purcell as Grant Gardner / Captain America:
Lorna Gray as Gail Richards, Grant Gardner’s secretary
Lionel Atwill as Dr. Cyrus Maldor / The Scarab
Charles Trowbridge as Police Commissioner Dryden
Russell Hicks as Mayor Randolph
George J. Lewis as Bart Matson
John Davidson as Gruber
Frank Reicher as Lyman
Al Ferguson as Detective (uncredited)
Howard C. Hickman as Lyman’s Attorney (uncredited)
Tom London as Mack (uncredited)
Edward Van Sloan as Gregory (uncredited)