Description
Mourners are gathered around an old man at his wife's grave. Overhead, an airliner heads toward Burbank, California. The pilot, Jeff Trent, and his co-pilot Danny are blinded by a bright light and loud noise. They look outside and see a flying saucer. They follow the saucer's flight until it lands at the graveyard, where the funeral's gravediggers are killed by an undead female.
At home, lost in his grief, the old man goes outside and (offscreen) steps in front of an oncoming car and is killed. Mourners, while attending the old man's funeral, discover the dead gravediggers' bodies. Inspector Daniel Clay and other police officers soon arrive, but Clay goes off alone to continue his investigation.
Trent and his wife Paula, who live near the graveyard, hear the sirens and Jeff tells Paula about his flying-saucer encounter, stating that the army has since sworn him to secrecy. As the saucer lands, a powerful swooshing noise knocks the Trents to the ground, as well as those at the nearby graveyard. Police Inspector Clay encounters the undead female and the old man's reanimated corpse, and they kill him. Investigating Clay's disappearance, Lt. Harper states: "But one thing's sure. Inspector Clay is dead, murdered, and somebody's responsible".
Newspaper headlines continue to report flying saucer sightings over Hollywood Boulevard, while a trio of the disks fly over Los Angeles. In Washington, D.C., the military fires missiles at more saucers, while the Chief of Saucer Operations, Col. Thomas Edwards, reveals that the government has been covering up saucer attacks. He mentions that one small town was annihilated, hinting at a secret history of other encounters.
The aliens return to their Space Station 7. Commander Eros informs their ruler that he has been unsuccessful in contacting Earth's governments. Eros therefore recommends implementing "Plan 9", resurrecting recently-dead humans by stimulating their pituitary and pineal glands. Meanwhile, Trent, concerned for his wife's safety, urges her to stay with her mother, but she insists on staying home. That night, the undead old man rises from his grave and breaks into the house. He pursues Paula outside, where his undead wife and the undead Inspector Clay join him in the pursuit. Paula is able to finally escape, but collapses from her ordeal after the three undead return on command to Eros' saucer.
At the Pentagon, Gen. Roberts informs Edwards that the government has been receiving alien messages: The aliens are trying to prevent humanity from eventually destroying the universe. The general dispatches Edwards to San Fernando, California, where most of the alien activity has occurred.
Though the walking undead are under direct alien control, Clay suddenly attacks and nearly strangles Eros for unknown reasons. The ruler closely examines Clay, then orders the undead old man destroyed to further frighten humanity. He then approves Eros's Plan 9 to raise armies of the undead and orders that they march on the capitals of Earth.
The police and Edwards interview the Trents, not knowing that the flying saucer has returned to the graveyard. Officer Kelton encounters the undead old man, who chases Kelton into the Trents' yard. Eros' ray hits the old man and his body rapidly decomposes. Edwards, the Trents, and the police immediately drive to the cemetery.
John Harper insists on leaving Paula in the car, but she refuses to stay alone, so Kelton stays with her. Eros and fellow alien Tanna send the undead Clay to kidnap Paula and lure the other three humans to the saucer. Seeing the saucer's glow in the distance, Trent and the police head toward it. At the car, Clay knocks out Kelton. Later, when he awakens, he calls for help and Patrolman Larry responds.
Eros lets Trent and the police enter the saucer with their pistols drawn. He informs them that human weapons development will inevitably lead to the discovery of "Solaronite", a substance that has the effect of exploding "sunlight molecules". Such an explosion would set off an uncontrollable chain reaction, destroying the entire universe. Eros now believes humans are too immature and stupid ("You see? You see? Your stupid minds. Stupid! Stupid!"), so he intends to destroy mankind. He threatens to kill Paula if Trent and the police try to force him to go with them. Officers Kelton and Larry arrive and see the undead Clay holding the unconscious Paula near the saucer. Realizing that their weapons are useless, they sneak up behind Clay and club him with a length of wood, knocking him out. Eros sees this and says Clay's controlling ray has been shut off, which released Paula. A fight breaks out between Eros and Jeff, but the saucer's equipment is badly damaged during the struggle, starting a fire. The humans quickly escape, and Tanna and the now unconscious Eros fly away in the now burning saucer. It finally explodes, killing them both, and the risen undead quickly decompose to skeletal remains inside their clothing.
In California, an old man grieves the loss of his wife and on the next day he also dies. However, the space soldier Eros and her mate Tanna use an electric device to resurrect them both and the strong Inspector Clay that was murdered by the couple. Their intention is not to conquest Earth but to stop mankind from developing the powerful bomb “Solobonite” that would threaten the universe. When the population of Hollywood and Washington DC sees flying saucers on the sky, a colonel, a police lieutenant, a commercial pilot, his wife and a policeman try to stop the aliens.
