If you pretend that the characters have neutral, possible names, the situation doesn't sound so arch; blackmail, after all, is a serious business. It all starts when Oggy Clay's tree house, topped with a propeller (for cooling) by mechanical Murk, takes off accidentally with Miss Shrubb and Arabella Serafin and Melinda Rose and her Very Important Visitor ZoZo Sejura also on board. Miss Shrubb has just been evicted from her hut in the swamp because Mayor Kronk wants to fill in the land for a racetrack; the children sympathize, especially activist Arabella who is equally up on the balance of nature and the misguided tyranny of adults. The successful flight, a secluded base, and the concern of their parents give her an idea--momentarily they have power and should make the most of it. When the youngsters, hovering over the town square, demand that the swamp be spared, the Mayor cries ""Blackmail,"" but he is forced to capitulate. Their second condition for return--simply that people care--sets strangers to talking and planning together. By this time the flying tree house has become an international cause celebre, with ZoZo's father, the Ambassador from Peroque, demanding his return and the Under-Secretary of State on hand to hear the third and last condition--peace in the world. Realizing, somehow, that she has overreached, Arabella breaks down, and the Under-Secretary tells her sadly that there's too much involved, they'd better come down and help. When they do, things are the same and not quite the same, which can be said of the story too--what starts as a predictably eccentric spoof becomes an often affecting critique and rallying cry which may succeed despite (or because of) its combination of disparate elements.