Swallows and Amazons Forever! The Big Six

Joe, Bill and Pete are members of the Coot Club which aims to protect wildlife, especially nesting birds. They spend most of their time on the river in their boat, the Death and Glory. Trouble starts when they're blamed for setting boats free from their moorings. Tom, Dick and Dot all become detectives and search for clues to lead them to the real culprit. They catch him just in the nick of time.