This Island Earth

Dr. Cal Meacham's flight to his laboratory ends when the Lockheed T-33's engine fails just before landing. A mysterious green glow surrounds his aircraft, seemingly saving him from a catastrophic crash. He lands shaken and begins to suspect something beyond ordinary physics is at play.

Back at the laboratory, Meacham discovers condensers delivered from a mysterious source. They appear to be made from an unknown, nearly indestructible material. He orders instructions and parts to build a device he doesn't recognize, the Interocitor.

Exeter appears on the Interocitor's screen, informing Meacham that passing a test proves his suitability for a secret research project. A beam is triggered by the device, causing it to self-destruct. Meacham remains intrigued and continues with the project.

Meacham is picked up by an unmanned, computer-controlled DC-3 and flown to a fog-shrouded area of Georgia. There he encounters an international group of top atomic scientists, including Ruth Adams, his old flame who does not recognize him. Meacham grows suspicious of Exeter and his assistant Brack.

Ruth Adams and Steve Carlson confide in Meacham, sharing suspicions about Exeter and Brack. They realize they are not being monitored and begin questioning the true purpose of the project. The sense of secrecy deepens the mystery surrounding their hosts.

Meacham, Adams, and Carlson flee the facility in a car as danger closes in. Their escape is thwarted when the car is attacked and Carlson is killed. The frantic flight intensifies the sense that something extraordinary is happening.

The trio escapes in a Stinson 108, witnessing the research facility incinerate behind them. Their aircraft is drawn up by a bright green beam and pulled into a flying saucer. The truth about Exeter's project begins to unfold as they are taken off-world.

Exeter explains that he and his people hail from Metaluna and are locked in a war with the Zagons. The Metalunans defend themselves with a planetary energy field but lack uranium, so they recruit humans to transmute lead into uranium. Time is running out for their defenses.

The interstellar travelers land safely on Metaluna, but the planet is under bombardment and its ionization layer is failing. The Monitor explains that Metaluna intends to relocate to Earth, a plan that would subjugate humanity by force. The gravity of the situation weighs on Cal and Ruth.

The Metalunan leader reveals a plan to relocate to Earth and subject humans to a Thought Transference Chamber. Exeter views this as immoral and misguided, creating a moral crisis for Cal and Ruth as their fate—and humanity's—hangs in the balance. The debate underscores the complexity of interplanetary politics.

Exeter helps Cal and Ruth escape from Metaluna, though he is badly injured in the process. A mutant guard boards the saucer and attacks Ruth, but dies due to the pressure barrier differences on the return journey. The escape marks a precarious pullback toward Earth as the planet's ionization fails.

As they enter Earth's atmosphere, Exeter sends Cal and Ruth away in their Stinson aircraft, declining to join them. Exeter is dying and the saucer's energy is nearly depleted. The saucer speeds into the ocean and explodes, ending the Metalunan mission while Cal and Ruth survive the separation.