The mare Gramp brings home seems perfect in every way; neither Lily, an experienced rider who has outgrown her pony, nor Gramp himself, a knowledgeable horse trader when he's not at work at his job on the town roads, can find anything the matter with her. Still, Gramp is cautious, warning Lily that she shouldn't set her heart on a mount that may not work out: there must be some reason she's been named ``Beware.'' Skillfully, Haas (Skipping School, 1992) uses the mystery about what proves to be an unalarming behavioral quirk in an otherwise sweet and exemplary animal to provide enough tension to hold this charming vignette together, offering a slice of rural Vermont life so simply and vividly drawn that it's next thing to being there. Illustrations not seen, but the jacket painting by Lindsay Barrett George is unusually appealing. (Fiction. 6-12)