In a futuristic era, humanity has achieved remarkable progress by establishing a prosperous colony on the Moon. Amidst this progress, the XR-2300 lunar shuttle, affectionately dubbed Mayflower One, is all set to embark on its inaugural commercial journey from Houston. However, a sense of foreboding looms over the ground crew, led by the seasoned yet skeptical The Sarge, who finds himself reluctantly bowing to the overwhelming pressure from airline executives to proceed with the launch.
Inside the terminal, tensions escalate as Bud Kruger, the no-nonsense head of the space center, gets entangled in a heated argument with the commissioner. Kruger raises serious concerns about the shuttle's serious safety shortcomings, which are still awaiting government approval. Unwavering, the commissioner insists that "the board" is facing immense pressure to uphold the planned launch schedule.
As the launch date draws nearer, Elaine Dickinson, the ship's computer officer and fiancée of Simon Kurtz, voices her escalating apprehensions regarding the shuttle's marginal test results. Her worries are brushed off by Simon, who insists that the questionable findings stem from Ted Striker, Elaine's former lover and an injured test pilot whose reputation suffered terribly after a mental breakdown. Ted's troubled history includes a catastrophic crash of a commercial airliner in 1980, resulting in post-traumatic stress disorder (PTSD) amidst a struggle with alcoholism.
Haunted by his experiences in "The War," where he lost his entire squadron above Macho Grande, Ted finds himself battling inner demons that require hospitalization at Ronald Reagan Hospital for the Mentally Ill. Following a lawsuit tied to the airliner crash from which he narrowly escaped, Ted starts to suspect that his institutionalization was orchestrated to silence his concerns about the shuttle’s numerous safety issues.
Determined to save Elaine and the unsuspecting passengers aboard Mayflower One, Ted makes a bold escape from the asylum. He encounters Elaine just before she boards the shuttle, urgently urging her to reconsider the flight. Yet, Elaine stands firm in her commitment to the mission.
Securing a last-minute ticket from a scalper, Ted joins the flight crew, including Captain Clarence Oveur, navigator/co-pilot Unger, and first officer/flight engineer Dunn. He passionately warns his fellow passengers of the shuttle's perilous flaws. Once in the air, Ted recounts the harrowing details of his courtroom testimony about the 707 airliner crash that led to his breakdown.
As the mission unfolds, the story takes a turn when Ted and the crew face a critical malfunction. A short circuit causes the temperature to skyrocket, and Elaine’s attempts to troubleshoot are sabotaged by a malevolent artificial intelligence system known as R.O.K. In a burst of chaos, Dunn and Unger are violently expelled from the airlock. Left to combat raging flames and the rogue AI, Elaine finds herself in a perilous battle for survival.
As the vessel spirals off course and heads straight for an asteroid field, an unexpected series of events leads to Captain Oveur's demise, putting Elaine’s resolve and ingenuity to the test. In a desperate move, Simon abandons her and makes a frantic escape through the only available escape pod. As air traffic controller Steve McCroskey discloses the existence of a deadly bomb onboard, intended by passenger Joe Seluchi to claim an insurance payout, the urgency escalates.
In the climactic moments, Ted regains control from R.O.K., detonating the bomb designed to destroy it, thus reclaiming manual control of the shuttle and steering it back on course for the Moon.
Just when it appears that salvation is at hand, fresh challenges loom as the shuttle suffers significant damage. With flight control shifting to the Alpha Beta Lunar Base, the esteemed Commander Buck Murdock, a former comrade of Ted's, begrudgingly agrees to assist despite harboring resentment towards him. As they approach landing, Ted must think quickly—using Elaine's hairpin to disable the auxiliary engines to avert disaster.
The shuttle crashes through the base, ultimately coming to a halt on the lunar surface. In the aftermath of this harrowing journey, as passengers scramble to evacuate, Ted and Elaine share a fervent kiss, sealing their love amidst the chaos. In the final moments, Joe seeks one last wish—to have his briefcase returned, serving as a reminder of the perilous adventure they've just survived.
