James Caan is top-billed as a scientist who is chosen over astronaut Robert Duvall for the upcoming NASA moon shot. In their haste to beat the Russians to the moon, the NASA folks have tried to sidestep several safety measures, but doctor Charles Aidman sees to it that every possible precaution is taken. When Caan makes it to the lunar surface, he stumbles upon gruesome evidence that the Russians had sent up a secret expedition themselves--and had fatally ignored all those extra security precautions which he's been subject to. Ted Knight, who received some of his best pre-Mary Tyler Moore roles in Altman's TV work, co-stars in Countdown.