Criswell, the narrator, kicks off the tale of GRAVE ROBBERS FROM OUTER SPACE, cautioning viewers about the shocking truths that lie ahead. As the story unfolds, we find ourselves at a small gathering around a grave as mourners pay their respects. An elderly man, played by Bela Lugosi, mourns for his recently deceased wife. Following the ceremony, a man reading from the Bible, Clay Stone, guides the old man away, with the others trailing behind. Just as two grave diggers commence their work, we see pilots Jeff Trent and Danny in a cockpit, discussing their landing approach with the Burbank tower. Suddenly, a mysterious flying saucer interrupts their routine.
The flight attendant, Edith, senses something amiss and enters the cockpit. Their unease deepens when the UFO lands in the graveyard, provoking a strange noise that sends the grave diggers fleeing. Amid this chaos, the old man is seen plucking a flower from his late wife's garden, overwhelmed by grief as the narration reveals he has left his home for the final time. The horrifying sound of brakes screeching fills the air as an ambulance rushes him to the hospital, where he meets his end.
Later, mourners visit the old man's above-ground crypt, baffled at how he is laid to rest above ground while his wife lies below. They remain oblivious to the fact that his resurrected wife, a vampire, lurks nearby, observing the scene. Panic ensues when a girl, played by Gloria Dea, screams upon discovering the bodies of the grave diggers. The police, led by Inspector Clay, arrive to investigate the mysterious deaths. Clay interrogates Larry, who informs him that the girl and another man discovered the bodies. Clay hands the investigation over to Lt. Harper, who soon notices an overwhelming stench emanating from the graves.
In a nearby home, Jeff and his wife Paula unwind on the patio, remarking on the surreal number of sirens they've heard that day. Jeff recalls a flying saucer he spotted during his flight, but before he can delve deeper, a saucer zooms by, knocking them over. This startling turbulence affects both the couple and the officers handling the bodies nearby. As Clay observes the saucer landing, he approaches the old man's crypt, where he is suddenly ambushed by the vampire and the old man, now risen from the dead, leading to a fatal encounter.
As the narrative progresses, the film's tension builds—newspaper headlines scream about "SAUCERS SEEN OVER HOLLYWOOD," prompting military intervention led by Colonel Edwards. They attempt to defend against the aliens, only to find their missiles ineffectual. The plot thickens aboard the aliens' mother ship, where Eros and Tanna convey their objectives to their leader: to activate Plan Nine—a plot involving the resurrection of the dead to create zombies.
Back at the airport, Jeff prepares to return to work but is distracted by his mounting fears about his wife's safety. Meanwhile, the old man, having transformed into a menacing figure, invades Jeff's home. Paula receives an eerie telephone call, and before long, she is confronted by the spectral figure, resulting in a frantic escape into the graveyard.
As police investigation resumes, the aliens' machinations lead to more chaos. The film showcases a myriad of confrontations between the living and the resurrected, highlighting societal and governmental inadequacies in addressing this otherworldly menace.
In a final showdown, a desperate battle unfolds on the alien craft, culminating in an explosive escape as the saucer—haunted by disaster—crashes and ignites over Hollywood. The narrator wraps up the tale with, >"God help us in the future," echoing the dire implications of the events just witnessed, leaving audiences to ponder the precariousness of their existence against alien forces.
