Flying saucers (wobbly ones at that) are visiting the Earth. For some reason they are bringing the dead back to life, including the rather unfortunate Bela Lugosi (this was indeed his last film). These zombies can be controlled by the aliens for their own nefarious ends. The police and military vaguely mill around and eventually confront the aliens including Vampira and Tor Johnson on their wobbly space saucer...
A very low budget film indeed, and often unintentionally hilarious (such as when a soldier is supposed to be standing in the open but you can see the wrinkles in the "sky" behind him). The acting veers between basic and terrible and the story is very confused (is this a science fiction film or a horror?)
It is wonderful though because of that, it's cult classic status is well deserved. Everyone needs to see this film at least once.