Margaret Hyde's books on driving, flight and atoms have made her a name in the teen-age non-fiction field. [Where Speed Is King, written with Edwin Hyde,] covers a concept through activities that have come to denote all kinds of speed. The fields where speed is king include running; skiing; car, horse and boat racing; homing pigeons; cycling; flight and so forth. Incidents both typical and well known,—for example, a description of the Landy-Bannister race in Vancouver or of Col. Stapp's physical endurance tests for rocket travel experiments, are efficiently told. They are the direct manifestations of speed, but they also serve to illustrate the more indirect—how endurance must be achieved through years of training, how an engine must be precisely tuned and so forth. Interesting reading about a quality that must be reckoned with today.