This movie is another hybrid of sci-fi and the horror genre. It is certainly a good example of the B-minus grade of movies. It has aliens (invisible ones, which saves on costuming) and space ships (invisible, of course, saves on props), and an army of zombies for the heros to defeat. If not expected to be too serious, Invisible Invaders can be entertaining.
Quick Plot Synopsis
Amid the pressures to develop better and better atomic weapons, a Dr. Noymann is killed during one of his experiments. An invisible alien inhabits and reanimates his body to deliver a warning to a cohort of his, a Dr. Penner. Unless the nations of the earth surrender to the aliens in 24 hours, they will invade and all human life will be destroyed on earth. No one believes Penner or his associate John Lamont. The aliens then deliver two similar re-animated-dead warnings to people at large. Panic ensues. No surrender comes by the deadline, so the aliens animate an army of zombies who start fires, blow up buildings, etc. The government asks Penner, Lamont and Penner's daughter Phyllis to hide out in a research bunker with a Major Jay. Much destruction afflicts the earth while Penner and Lamont try one failed idea after another to create a weapon against the aliens. They capture an alien-infested zombie by encasing them in acrylic. They bring the encapsulated alien into a sealed test chamber in the bunker in order to test ideas. None work. In frustration, Lamont throws a beaker of fluid at Jay which causes electrical shorts and loud alarms. Penner notices that the loud sounds affect the zombie. They then construct a sound gun. It works. The aliens are jamming their radio communications, so they have to defeat the hoard of zombies and go find the invisible ship to destroy it. This they do and radio in their discovery. The world is saved and learns to live together in harmony. The end.
Why is this movie fun?
It's somewhat fun to see (or hear) veteran B-grade sci-fi actors like John Carridine and John Agar at work. Despite the predictable script, the pace moves along fairly well. A few plot surprises keep it from being totally predictable. Knowing that Invisible Invaders predates the big-time zombie movie Night of the Living Dead by nine years is kind of fun.
Cold War Angle
The attempted moral of Invisible Invaders is preaching nuclear disarmament. Penner starts the movie as a lone voice advocating disarmament. The heavy-handed moral statement comes at the end (though it's a non-sequetor to the story line)."Out of the destruction of war, in which a dictator of the universe had been defeated, a lesson had been learned. The nations of the world could work and fight together." Instead of a Cold War, we should all be friends.
Plan 8 From Outer Space? -- Invisible Invaders was released prior to the much more famous Plan 9 From Outer Space which also featured aliens trying to take over the earth by re-animated dead humans. Plan 9 was produced earlier, but the two films appear to have been developed in parallel rather than one spawning the other. For some reason, zombies became quite the hot marketing item in the late 50s. Zombie flicks were assured of selling drive-in tickets, no matter how lame.
Don't Need No Body -- One shouldn't expect thoughtful continuity in B-minus films, but... The aliens say they must inhabit (re-animated) dead humans in order to kill people. They're invisible, sure, but they're not insubstantial. They leave draggy foot prints in the dirt. They push bushes aside, They can hit people and knock them down. They really don't need human bodies. Still, zombies make for a creepier army.
Interplanetary Procrastinators -- Zombie Noymann tells Penner that they had invaded earth's moon 20,000 years ago, defeating the civilization there. (the catwomen?) Now it was earth's turn. Why, after tens of thousands of years, were they in such a hurry that they had to issue a 24 hour ultimatum? And just what were they going to do with earth if it had surrendered? Would the aliens not have invaded? What then?
Bottom line? If you like old zombie movies, this is one you should catch. It's cheap and kind of campy, but that's pretty normal for the genre. If you like sci-fi and aliens, you'll be a little disappointed. There is a smattering of "science", what with the whole sound-gun thing, but it's a little thin.