The Cape Canaveral Monsters

The alien beings took control of the corpses left behind after the car crash. The man and woman died in the accident, but their empty bodies were instantly inhabited by the extraterrestrials Hauron and Nadja, reanimating them into new hosts for their mission.

The opening sequence shows white circles stating their mission to inhabit human bodies.

The aliens conducted a covert campaign to sabotage the United States' space program, endanger the nation's launch efforts, and ultimately prevent the US from reaching space. Their goal was to disrupt American space exploration from within.

During a nighttime reconnaissance of Cape Canaveral, guard dogs attacked Hauron and tore off his reattached arm. Later, after capturing Bob Harding, the alien Nadja removed Bob's arm and grafted it onto Hauron, also replacing Hauron's scarred chin with Bob's to improve his appearance.

Earlier, Nadja promised to reattach Hauron's severed arm at their laboratory.

Bob Harding died during capture by the aliens. Both Bob's body and Shirley were then transmitted to the aliens' planet, despite Bob being dead and warnings about sending damaged specimens. This indicated the aliens were collecting human specimens for their homeworld.

Nadja mentioned the cave served as a breeding ground for experiments.

Tom discovered that his wristwatch with a radium dial could disrupt the electromagnetic field holding him captive. He waved the watch at the device, breaking its hold on him and allowing him to escape to summon help.

Hauron used a disruptor ray to sabotage rockets as they launched. The alien would target the missiles mid-launch, causing them to explode. The human scientists were puzzled by these failures and remained unaware that extraterrestrials were behind the sabotage.

Hauron wielded a disruptive ray while reconnoitering the launch site at night.

The artificial cave served as the aliens' headquarters, laboratory, and breeding ground for their experiments. It was their base of operations for carrying out the sabotage campaign against the space program.

Sally's father, the head rocket scientist, devised a plan to block the aliens' transmission. The humans escaped the cave just as a powerful explosion destroyed it, preventing Nadja and Hauron from transmitting themselves home. The aliens were eliminated before they could flee.

The ending is ambiguous. While the immediate alien threat appears neutralized with the cave's destruction, the final scene shows Sally and a deputy driving away when tires screech, a crash occurs, and Sally screams, leaving their fate uncertain and suggesting the danger may not be fully over.

The summary notes the resolution is uncertain and the ending is intentionally ambiguous.

Nadja and Hauron could revert to their original circular form to transmit themselves home. When confronted by the rescue party, they attempted this method to escape, but the humans devised a plan to block their transmission before destroying the cave.

Nadja chose to graft Bob's chin onto Hauron because she claimed Bob had a handsome chin. This cosmetic modification reflected the aliens' interest in improving their human hosts' appearance, even while carrying out their hostile mission.

The aliens operated covertly from their hidden cave laboratory, using their disruptor ray remotely during rocket launches. The sabotage appeared to be mechanical or technical failures, leading Tom to initially suspect an illegal human transmitter rather than extraterrestrial involvement.