Armed with only his kalimba, Joshua doesn't think he's going to make much of an impression in the talent show—especially after he sees the way classmates Kareem and Shamika boogie. But a generous gift from Uncle Zambezi—an African mask that grants wishes—changes his mind; after turning himself first into Kareem, then into a famous rap star, and finally into the mayor (``someone the kids would all respect''), Joshua reverts to being himself just in time to rescue the show from disaster and brings the audience to its feet. Rich's full-page acrylics place Joshua in a cleaned-up inner-city neighborhood; warm colors and occasional comic touches (a dog watches bug-eyed as Joshua switches instantly from ``Righteous Rapper'' to gray-suited official) reflect the happy tone. A sturdy picture-book debut for both author and illustrator. Brief explanatory afterword. (Picture book. 6-8)