Veteran Warnes creates an idyllic, ground-level (until the end, anyway) woodland setting for this debut tale of a young rabbit’s search for a promised surprise. Daddy’s planning something, and curious little Creamsicle-colored Rosie sets out to discover for herself what it might be. Fellow creatures she meets won’t give it away, but furnish clues: It’s acorn-shaped, says Squirrel; you can go into it, claim the burrowing moles; it’s blue as an egg, hints a bird. What could it be? Young followers will sympathize with Rosie, who finally takes a tumble down a hillside: “ ‘I’m tired of looking and hopping,’ she said, rubbing her bumped bunny nose.’ ” But there’s Daddy, at last, and his truly grand surprise—revealed in a climactic fold-out as a basket beneath huge blue balloon—banishes all weariness: “ ‘Now I can see the whole wide world!’ ” Readers will definitely share Rosie’s delight. (Picture book. 5-7)