Captain America was a 1944 Republic black-and-white serial 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!
The serial sees Captain America, really District Attorney Grant Gardner (played by Dick Purcell), trying to thwart the plans of The Scarab, really museum curator Dr. Cyrus Maldor (played by Lionel Atwill) – especially regarding his attempts to acquire the “Dynamic Vibrator” and “Electronic Firebolt”, devices that could be used as super-weapons.
Republic changed the usual plot element with regards to the villain of Captain America. The studio’s usual approach was the use of a mystery villain who was only unmasked (as someone we would know from the serial) in the final chapter. Instead the secret identity of the villain was known to the audience from the beginning, thus adding more tension for the audience.
The plot opens with news of multiple 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 realises 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. realises 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 organised 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!