A fearsome thing is a thing you're afraid of--and it has nothing whatever to do with whether others are afraid, nor with whether it is in fact dangerous. It's your view of the matter that counts!
In exchange for the promise of an almost limitless fuel, earth agrees to allow the alien Grdnzth people to gather on earth for transit to a planet as their is going to be destroyed. The Grdnzth are ugly, looking rather like reptiles. They also pop in anywhere, anytime unannounced. It's the job of PR men Pete Greenwood and Tommy Heinz to get the public to accept the Grdnzth and the inconvenience...
"Well, Corporal Westerburg," Doctor Henry Harris said gently, "just why do you think you're a plant?" As he spoke, Harris glanced down again at the card on his desk. It was from the Base Commander himself, made out in Cox's heavy scrawl: Doc, this is the lad I told you about. Talk to him and try to find out how he got this delusion. He's from the new Garrison, the new check-station on Asteroid Y-3, and we don't want anything to go wrong there. Especially a silly damn thing like this!