Ernst, known for funny watercolors and fractured fairy tales, makes a startling departure from her norm in this design-heavy alphabet book. As the title promises, readers will be rotating the book to see how the brightly colored cut-paper letters change with each 90-degree turn. Each letter is set into a black-bordered square against a harmonizing negative space; the hand-lettered text appears in white, turning as needed along the border. The narrative itself imagines the secret lives the letters yearn for, as “B masquerades as / a pair of goggles, / half a butterfly, / two windows in a castle tower.” On any given page, the image may be created by the letter itself or by the negative space surrounding it, so the interstices between the legs of an E become an electric plug, or (in a moment of great inspiration) the yellow triangles formed by a green N become “two tortilla chips headed for guacamole.” The act of turning the book 104 times in all (4 X 26) can become tedious, but the novel concept freshens up the canon of abecedaries. (Picture book. 4-8)