Jane Farrow wakes up in the middle of the night in her hospital bed and complains to the nurse that the moonlight through the window is keeping her awake. However, she insists on keeping them open so she can see the moon. Her husband, Tom, is aboard Trailblazer 1 and there's been no news of the ship's arrival, scheduled for the next morning. When Jane wonders if any reporters have come for a story about her car crash, the nurse assures her that they don't give out information and asks if Jane wants her immediate family notified. Jane refuses, saying that she doesn't want her husband to find out about her accident and become distracted.
As Trailblazer approaches the moon, Communication Officer Tom Farrow listens to the radio broadcasts from around the world and translates for his fellow crew: Robbins and Bruegel and scientists Peter Riber and George Batton. He has a photo of his wife taped to his console, and is surprised when they get a news broadcast about Jane's accident. McCauley tells him to switch it to the radio beacon channel so they can confirm their course. Tom does so, but makes a mistake and gives McCauley the wrong coordinates.
The ship touches down and the other crew heads outside to conduct their experiments on the moon's crust. Once everything is secure, McCauley lets Tom contact Ground Control to get an update on his wife's condition. The colonel tells Tom that Jane would want him on the expedition despite her condition and Tom admits that he's right.
Over the next six days, the six-man crew detonates explosives and record the seismic readings. On Earth, Jane listens to the radio as they announce that Trailblazer will return the next day.
The crew head out for the last series of tests. While they wait for Tom to join them in the airlock, Robbins objects to being partnered with him. He complains that the communications officer used a double-charge the previous day and almost got the two of them killed. McCauley reassigns Robbins and partners with Tom, while Riber tells Robbins not to be so hard on Tom. Robbins points out that his wife is expecting and he wants to survive to get home to her. Tom arrives and Robbins harasses him until McCauley tells him to stop. As the others go out, McCauley tells Tom that Jane will be fine and advises him to get control of himself.
Robins and Bruegel set off the next explosion while Riber monitors the seismograph from the ship. Riber then informs Dr. Strauss, the project head on Earth, that they have the readings he needs.
McCauley, Tom, and Batton set off the last explosion, but it triggers a moonquake. Tom is separated from the others and falls into a fissure while Trailblazer topples over, knocking Riber unconscious. Batton boards the ship to confirm that his colleague is okay, revives him, and tells Riber that Robbins and Bruegel are heading back to the ship while McCauley finds Tom. The two scientists check the radio and realize that it was damaged in the crash, and that Tom is the only one who has even a chance of repairing it.
At Ground Control, the general in charge tells his men to start checking when they don't hear from Trailblazer after two hours.
When the fissures caused by the moonquake slow him up, McCauley takes advantage of the one-sixth gravity to leap over them. He finds Tom at the bottom of a shallow fissure and confirms that his radio was broken. After pulling Tom out, McCauley discovers that the communications officer has twisted his ankle and uses his short-range radio to call the ship and have Bruegel and Robbins bring them spare oxygen tanks.
With their oxygen running out, McCauley and Tom come to a fissure too wide to jump. The colonel is ready to sacrifice his oxygen to get Tom back so he can fix the radio and save the others. The two astronauts arrive and throw the oxygen tanks across, and McCauley has them bring a section of the ship's ladder to create a makeshift bridge. McCauley crosses first but Tom slips on the way across and just manages to crawl to safety.
Jane dozes off after reading a newspaper article about the missing ship. The nurse inadvertently wakes her and Jane insists that she knows Tom will find a way back to her.
Tom gets back to the ship and informs the others that it will take him at least thirty hours to make repairs. He begins working without sleep until he completes repairs. McCauley tells Ground Control of their situation and the general sends a rescue ship. Meanwhile, the others are amused to discover that Tom has dozed off.
Once the crew are back on Earth, Tom and McCauley go to see Jane. The happy couple kiss while McCauley offers flowers for her on behalf of the crew, and Jane sheepishly admits that as the wife of an astronaut, she should never look up when driving.