As you might expect from the title, this movie doesn't take itself too seriously. FBI agent Rex Armstrong (James Raspberry) is awaiting the airplane delivery of two convict brothers that he helped capture, Bart and Bert Brazzo (John Gillick and Lawrence Hall). On the way, the airplane runs afoul of some aliens, who team up with the Brazzo brothers to start a diabolical plot to take over the world via a secret formula in a soft drink from a local factory. This formula turns anyone who drinks it into a zombie. The aliens also have this little sphere that can zombify people, among other things. Rex and his partner Ace Evans (Larry Raspberry) have to figure out what's going on before it's too late.
The G-men are supposed to be deadpan, but good deadpan has a depth that these guys lack, and they merely come off as flat. The aliens are supposed to be emotionless, and they carry that off a little better, but then you have four of the main actors displaying no emotion. Thank God for the Brazzo brothers, who bicker, plead, get irate, and otherwise emote, saving the movie from being completely without interesting characters.
Writer/director Marius Penczner appears to have been going for an homage/satire of G-Men movies, since the film is shot in black and white, the heroes are your typical squeaky clean government agents of that genre, and the sets, props, and costumes all have the look of that era. However, the satire is not sharp enough to be funny, if that was the intent, and if the intent was just to emulate the genre, well, I think it was a success, but then you're emulating a genre that really didn't put out a lot of hit movies. The end result is rather lackluster.
The plot can be a little muddled at times, but generally you can follow what's going on. This is a nice little time-waster, but ultimately forgettable.