Set after WWII in an alternative timeline. A rogue admiral from the Imperial Japanese army is secretly building a new underwater armada that will soon begin an unstoppable offensive on the free world... And a suicidal mission of a lone Soviet Commando Frogman who must thwart the evil plan by diving in an experimental bathyscaphe to the bottom of the oceanic trench somewhere in the Pacific, and setting off an atomic bomb...

Here is a teaser video: https://www.youtube.com/watch?v=O0BkUWuEx8E