It's pretty obvious as you watch CAPTAIN SCARFACE that the film was made for a relatively small budget and starred lesser actors. It's also obvious that the "big name talent" for the film (Barton MacLane) was given a very weird and unconvincing role in the film. He plays Captain Scarface--a Russian maniac who sounded most of the time like he was doing a Bela Lugosi impersonation. While MacLane is a fine villain in films, he never really had a lot of range--this assignment was clearly outside his abilities. However, despite this as well as a rather abrupt ending to the movie, the film does work reasonably well--thanks to good writing.
The plot involves a duplicated merchant ship that replaced the real one once it was torpedoed. The plan is to sail this fake cargo ship into the Panama Canal and explode an atomic bomb on board. The baddies are all Russian Communists bent on harming America. However, what the Ruskies don't know is that an American (Leif Erickson) has replaced a Russian collaborator, as he is sure something is amiss with this strange boat. With Erickson's help, the few passengers aboard the ship learn that death awaits them and so they work together (mostly) to stop the attack.
This film is an interesting curio from the Red Scare and came out the same year Stalin died. Today, many might see the film and laugh at its seemingly paranoid and silly plot, but at the time this sort of film appealed to fears that Communism would engulf the globe. It gives us some insight into the people and the times. And, unlike some propaganda films of the era, this one is reasonably well done and quite interesting. Well written, aside from a very abrupt ending, it's worth a look.
By the way, you gotta love the way they chose names for this film. One of the guy's names is Perro ("dog") and the boat is called the El Baño (though it's missing proper accent mark) which means bathtub or bath. Pretty goofy.