Well known in other fields (remember her Farm Wanted in 1951?), this is, we think Mrs. Hilles' first juvenile. It somehow doesn't quite come off, though the theme is a good one- the adapting to an American way of life on the part of Pierre, who ends by wowing the Fourth Grade when he proves his kinship to his chef father in preparing ""pommes soufflees"" for the P.T.A. There's an engaging description of Pierre perched on a stool, wielding his two frying pans and his frying basket. But in the main there's lack of seasoning, a flatness of telling that kills the joie de vivre. Jay Hyde Barnum's drawings making up for some of the missing seasoning. Cloth, reenforced.