Hubert wants to see the circus that's coming into town more than anything, but unfortunately, he has no money, and no chance of getting it from his father. When he learns the human cannonball quits, he decides he will become the replacement. With the help of his friend Slider, the two build a rocket, one that shoots him into the wrong garden shed. The new, mysterious, and intimidating neighbor, Mrs. Pomfrey-Parkinson, is hiding more than just garden tools away in the shed. Hubert accidentally finds himself in an alien spaceship, and learns of Mrs. Pomfrey-Parkinson's reason for being on Earth, to take it over. ( )