[Folk-magic] is tricky to set up. In The Ogre Downstairs … Diana Wynne Jones goes to town on something far more practical: a magic chemistry set. Caspar, Johnny and Gwinny feel oppressed by their new stepbrothers and irritable stepfather: the magic experiments at once liberate them and bring them further into opposition (the stepbrothers have a magic set, too). This may not sound like anything very much, but the adventures are beautifully propelled and sustained by Mrs Wynne Jones's imagination, working much on the level of [H. G.] Wells's Magic Shop. Who could resist animated toffee bars that seek the warmth of a radiator and melt, eat sweaters and can't easily be drowned? The children fly, shrink and change colour, but none of this seems overdone: the physical consequences of each experiment are described in ingenious detail, and the last episode involving Dragon's Teeth warriors in the shape of...