Mallory felt she knew Woody well enough to be sure that absolutely nothing could ever make her glad of his presence."" Left alone with her nerdy stepfather for a weekend, the nine-year-old promptly makes a forbidden bike ride to buy candy, which she shares--but ungraciously. To her horror, the butter cream shrinks Woody to three inches tall. Mrs. Peebles, who sold the candy accidentally, assures Mallory that her inventive husband has the antidote--if Mallory can contact him. Meanwhile, Woody, aided by the unflappable Mallory, courageously meets a variety of misadventures. When they do find Mr. Peebles (working as a fortuneteller), the antidote fails, but Mallory is finds a clever way to effect a reversal; and by the time Mom returns, she's realized that it's ""not easy trying to learn how to be a stepfather."" Funny and fast-moving: light reading with a worthwhile message. Inviting format and crisp, diminutive llustrations help sell the story.