On holiday with their mother in the Lake District in 1929 four children are allowed to sail over to the nearby island in their boat Swallow and set up camp for a few days. They soon realise this has been the territory of two other girls who sail the Amazon, and the scene is set for serious rivalry.

• Theatre Projects Film Productions Ltd.
• Virginia McKenna
• Ronald Fraser
• Suzanna Hamilton
• Simon West
• Sophie Neville
• Stephen Grendon
• Kit Seymour
• Lesley Bennett