. . . led spoiled little rich girl, Candy Bascombe, who was spending a season with other boys and girls at Summer House, behind the walls of a neighboring estate. With Huggins Pindar and John Addams, Cindy deciphers a strange code in an abandoned playhouse to unravel the tangled skeins of an old quarrel in the Howard family. As Candy and the boys expose Guy Howard, director of the Modern Art Institute in Capitol City, and the art forgeries he has forced his weakling brother Martin to execute, she loses the snobbish attitudes which had antagonized other children earlier. In a standard- brand finale, the reader discovers that half the cast of characters are second cousins, a consummation at which adult minds would balk -- but young readers will probably swallow it whole.