Diana Wynne Jones at her finest — family feuds and chaos, magic with hilarious results and some of the most original ideas ever to appear between the covers of a book. Casper, Johnny and Gwinny get a big shock when their mother Sally marries the Ogre. He is large and stern and not at all interested in children. His first wife left him years before – and the children aren't in the least bit surprised, considering what the Ogre and his two sons, Douglas and Malcolm, are like. Now the five children and two adults are squashed under the same roof, it's not surprising tensions are running high. Then the Ogre brings home the Chemistry Sets – one for Malcolm and one for Johnny. That's when the fun begins, as each side of the family discovers that these are no ordinary chemistry sets…