The Ogre buys chemistry sets, one each for Johnny and Malcolm. It is not too long before the children discover that some of the chemicals have magical properties. Douglas and Malcolm discover this after Johnny accidentally makes Gwinny fly, and a race begins between the two groups to find out which chemicals are magic. Caspar, Johnny, and Gwinny go flying, but the effect wears off away from home. Douglas has had to visit the mysterious store the chemistry sets came from to find out the antidote for a chemical which has turned Malcolm small, and they are able to attract his attention. He assists them in getting home, but the effect wears off again as they approach, which leaves Douglas stranded outside the house. Douglas (the oldest of the boys, perhaps fifteen) is caught by the Ogre, who assumes he has been sneaking out, and strikes him. The Ogre also strikes Johnny and Malcolm later in the book.