A mysterious present of a crate of pineapples from Puerto Rico provides the stepping stone to another adventure for the venturesome Hollister children. The fruit turns out to be a gift from a school friend of their mother's who had married a Puerto Rican doctor. On a subsequent visit to Puerto Rico the kids find not only an old Spanish crown but help trap the crooks who are after it. If this kind of thing is meant as a vehicle for information about other people, we are wondering how much wears off on children who are in search of blood and thunder rather than the finer points of Spanish hospitality, housing, food, etc.?