Deciding that her overgrown privet bush is about to take over her garden, Polly snips it into a giant, sweet-looking topiary bird that she rides aloft on an adventure: she rescues a child who has fallen from a boat. Later, after a storm, the bird carries Polly to fetch groceries for her stranded neighbors. Only the children notice her extraordinary steed: ""Well, if they won't look they won't see,"" they observe of their parents. Finally, the grown-ups do see--but when they visit Polly's garden, the privet has reverted to its former shape and they laugh at their own foolishness. ""Well, if they won't believe, they won't know,"" say the children to Polly. The adventures here are stock, the message familiar; but Cartwright's telling is graceful and lively, while her husband's crisp, bright paintings are outstanding. His characterizations are slyly satirical, his bird a quietly imaginative pleasure, his light-bathed compositions mesmerizing. All in all, an appealing fantasy.