Overview: Miguel has entered himself and Robin in a boomerang-throwing competition. But neither knows how to throw a boomerang properly. They get a demonstration on boomerang flight from a professional. In California, Kathy flies an ultralight with a test pilot.Film inserts: indoor airplane flying at Columbia University leads a boy to building a model airplane; the need for great amounts of energy for birds and airplanes to fly.ANIMATION: The four forces involved in flying.THE BLOODHOUND GANG: ""The Case of the Bottled Boat, Part Two."" Armed with a ticket to the Maritime Museum, the gang talks to a model shipbulider who tells all he knows about the stranger with the bottled boat. He's a regular customer, buying ships every week, always with a specially-marked pennant on the mast. (Concludes in next episode.)