"Undersea Kingdom" could be compared to Universal's popular "Flash Gordon" serial which was released the same year. However, instead of having the story take place in outer space, this one is at the bottom of the sea in the lost continent of Atlantis complete with a madman trying to take over the world and a similarly named hero.
Unga Khan has harnessed the atom and is causing earthquakes across North America. Scientist Professor Norton meanwhile has invented a ray that will counteract the earthquakes which he believes are coming from the ocean floor.
As luck would have it the ever resourceful Norton has also invented an atomic powered submarine with which he plans to descend to the ocean floor to discover the source of the carnage. He forms a team which includes "Crash" Corrigan (Ray Corrigan) a naval lieutenant and a muscular athlete (who gets to run around without his shirt for most of the story), Diana Compton, the ever present newspaper reporter, young Billy (Norton's son), Norton's assistant Joe and for comic relief Briny and Salty.
When the sub descends into the ocean it is discovered by Unga Khan who using a tractor beam pulls the crew into the undersea world of Atlantis. There, Crash and the gang discover that there are two warring factions; Khan's Black Robe Guards and the White Robed followers of Sharad. The Black Robes posses a tank-like machine called the Juggernaut and an army of walking garbage can robots called Volkites.
Can Crash Corrigan save the day? You bet he can. But it will take 12 episodes for him to do so...
Ray Corrigan .... Crash Corrigan
Lois Wilde .... Diana Compton
Monte Blue .... Unga Khan
William Farnum .... Sharad
Boothe Howard .... Ditmar
Raymond Hatton .... Gasspon
C. Montague Shaw .... Prof. Norton
Lee Van Atta .... Billy Norton
Smiley Burnette .... Briny Deep
Frankie Marvin .... Salty
Lon Chaney Jr. .... Capt. Hakur
Lane Chandler .... Darius
Jack Mulhall .... Lt. Andrews [Chs. 1, 12]
John Bradford .... Joe [Ch. 1]
Malcolm McGregor .... Zogg