Three Earthmen are shocked to encounter "themselves" when their expeditionary force arrives on the planet Xanra. As part of a military coup, natives of the planet have disguised themselves as the three Earthmen as part of a plot to imprison the real expedition and convince their government that Earth was there to take over.
In far-off 1995, young Earthboy Tommy Keen has won the right to represent Earth in the Interplanetary Quiz Kid Competition. The contest involves a race to the "Black Planet," picking up objects along the way, and avoiding interstellar obstacles. Tricky enough to do on its own, but when Tommy finds thieves trying to steal the planet Venus, things get even more complicated.
Aliens convince an Earthman drifter that he is their legendary king, who one day would return to them. As their king, they take him to the sacred gem garden to collect (what else?) gems. But the "king" figures out it's a scam, and has to figure out how to escape.