A mysterious message in a bottle is found inside the stomach of a shark. It contains three notes, each in different languages. Together they appear to contain clues regarding the location of Captain Harry Grant, a man lost at sea for two years.

With this information in hand, Lord Glenarvan and the children of the lost Captain set off on a yacht to find the missing seaman. Danger, intrigue, and mystery unfold around them as they adventure forth, across countless miles of sea and through three different countries.

Also known as Round the World: New Zealand, Among the Cannibals.