Here's a popular radio program put into book form, a program carried on more than 80 stations and widely publicized. Two main adventures in the undersea land where lost things go will make young readers turn the dial for more of the kind, for there's an adroit blend of fantasy and stream-lined modernism in the story and its details. Isabel loses her red-haired doll, Henrietta, overboard, and she and Billy let loose a giant fish that Billy has caught when he promises to take him down to the Land of the Lost to see Henrietta -- and the jackknife Billy had lost, and all the other exciting things. One part of this strange country has toys, another table silver, and weird creatures of all kinds, including some pretty dangerous enemies, confront them. Good magic helps them out, and Billy is able to act as character witness when his favorite Jackknife needs help to get into the order of the Knives of the Square Table. An ingenious story, which occasionally descends into puns which will bother grown-ups more than children. And the colored illustrations by Olive Bailey are sure passport to popularity. The story recalls some of the flavor of that magic tale of years ago, The Little Spotted Seal -- story of the land where imaginary playmates go. Cloth.