As the excitement mounts for Capricorn One, which is set to be the first crewed mission to Mars, three astronauts—Charles Brubaker, Peter Willis, and John Walker—are swiftly removed from the launch pad, leaving them bewildered and alarmed as they are taken to a remote military installation in the desert. The public remains oblivious to the shocking revelation that the spacecraft they believe has launched is actually uncrewed.
Upon their arrival at the base, NASA official James Kelloway discloses a dire scenario: a crucial life-support system malfunction could have led to catastrophic failure. In a harrowing turn of events, Kelloway coerces the astronauts into producing televised footage that will mislead the world into believing they successfully traveled to and landed on Mars. The situation escalates when Kelloway ominously hints that their families could suffer severe repercussions should they refuse to comply.
Trapped at the base, the astronauts must recreate a Martian adventure while a select few at NASA are in on the deceit. However, an alert technician named Elliot Whitter makes a troubling observation—the crew's live broadcasts reach ground control ahead of the telemetry data from the spacecraft. This alarming discovery sparks Whitter's investigation, leading him to confide in his friend, Robert Caulfield, a TV journalist. Yet, Whitter's sudden disappearance sends Caulfield on a dangerous quest for answers, where he finds himself targeted by those who want to keep this sprawling conspiracy under wraps.
As the empty spacecraft re-enters the Earth's atmosphere and risks destruction due to a faulty heat shield, the astronauts realize they must escape and expose the truth. They separate in an effort to enhance their chances of finding help, but Kelloway is quick on their trail, deploying helicopters to hunt them down. While Willis and Walker are ultimately captured, Brubaker manages to slip through the net. Caulfield, investigating his missing colleague, discovers a perplexing televised exchange involving Brubaker's wife that hints at a deeper narrative—a family vacation entangled with a cover-up concerning film special effects.
Determined to untangle the web of deception, Caulfield gets a tip about an abandoned military base, located 300 miles northwest of Houston. There, he uncovers irrefutable evidence of Brubaker's presence, including a distinctive necklace and medallion. With the help of veteran crop-dusting pilot Albain, Caulfield embarks on an aerial search that leads them to an isolated gas station, where they find Brubaker in the midst of evading capture.
In a breathtaking sequence, Albain demonstrates his skilled flying by expertly maneuvering his plane, managing to blind the helicopters chasing them with a spray of crop dust, causing their pursuers to crash. As they successfully rescue Brubaker, the trio heads toward a memorial service for the astronauts. There, Kelloway and Brubaker's wife converge, setting the stage for a shocking revelation that will unravel the full extent of the conspiracy before a live audience. The nation holds its breath as the facade crumbles, leaving viewers to reflect on the profound ramifications that will emerge from this elaborate charade.
