Gr 2-4 Meg Mackintosh joins the ranks of Encyclopedia Brown and Cam Jansen (Viking) as the latest child sleuth with whom readers can match witsbut she provides the challenge to slightly younger mystery buffs. Here Meg tackles the half-century-old mystery of the whereabouts of her grandfather's autographed Babe Ruth baseball, hidden by his cousin, who left a series of Mother Goose-related clues. The clues are simple enough that youngest Sherlocks will be able to keep up with Meg, although they will find that success in applying the clues to the mystery's solution requires careful attention to details in the art as well as the text. The format is inviting, with large type and numerous lively pen-and-ink sketches giving the book an open look. Meg is a determined, clever and resourceful protagonist, and children will want to see more of her. David Gale, ``School Library Journal''