A good mystery, credible enough and not too complicated, a good story, and nice writing -- so here is an answer to the incessant demand from ten up, for mysteries and yet more mysteries. This fits the upper bracket of this age group, and on up to fifteen. Four cousins go to spend the summer in an old Cornish village; they meet Sam Penmarth, a boy of their own age, living in a sinister, gloomy old mansion with an uncle who is an archeologist. They form a club -- they find a hidden room and a confession of an ancient crime. Lively ingenious youngsters, whom everyone will like, and a background of the days of smuggling as the setting for the crime.