A classic scenario—stage-struck but paralyzingly shy, little Liza Shetland (a sheep) rises to an emergency, saves the show, and becomes a star—is presented with unusual wit and panache. From the beginning, Liza's dreams of glory are amusingly at odds with her stage fright; she can't bring herself to tell Dad what she wants for breakfast, let alone try out for the big part of ``Amelia Ewehart'' at school. Still, she learns the lines while working backstage, and when Cashmere, so cool at tryouts, suddenly freezes with a terror surpassing Liza's own, she's ready. Levine's text, brisk and funny, has an undercurrent of sympathy that recalls Kevin Henkes's books. Lanfredi's humans-as- sheep are delightfully caricatured in vigorous line and sunny colors; the kids waiting to audition, a distraught teacher, and an audience of expectant parents are a hoot. (Picture book. 4-8)