The head of Mission Control, Simms, watches with his team as a rescue craft lands on the Moon and an astronaut, Steve, emerges to look for the wreckage of two other ships. Steve transmits what he sees via camera. He arrives at the crash site and confirms that the first ship, the mothership, crashed. However, there is no sign of the second ship. Simms confirms that while they were in contact with the mothership crew after the crash, they have now disappeared without a trace.
Simms meets with the reporters and briefs them on the situation. Two ships landed on the moon as part of a colonization effort. The mothership crashed and there is no sign of the second ship. They sent a rescue ship but so far it has found no signs of the missing ship. When asked, Simms denies that any of the United States' enemies could or would be involved, and there is no other life on the Moon.
Simms is called back to Mission Control where the rescue astronaut has reported the discovery of a large metal construct. It is 30' x 15' with an odd lever device and springs, and was built from the components of the second missing ship. Steve's signal starts to fade out. He realizes what the construct is but before he can explain, they lose visual and the men in Mission Control hear his scream.
Simms reviews the footage with the astronauts and one of the reporters realizes what the construct is: a giant mousetrap. A few minutes later, they reacquire the video signal and see a giant mouse approach the giant mousetrap.