A first rate mystery story, with the identity of the boy who is boarding in a doctor's family, as the pivot on which the story hangs. The family is well done, the relations of parents and children, and of the children to each other -- and of the problem of the shy stranger is a good build-up for his sudden disappearance, foreshadowed by inquiring strangers and midnight escapades. Then the kidnapping -- and the search. Well sustained -- well written -- and good reading for all ages. California setting.