The Famous Five are George, Julian, Dick, Anne and Timmy the dog. They are spending their first summer holidays together and are already off on an exciting adventure! Their very first trip to the beach and they find not only an old smugglers' cave but also make a thrilling discovery: George's father Quentin, a famous inventor, is going to be kidnapped! The professor has established a laboratory on rocky Kirrin Island and is working on a brand new and highly clever way of creating energy. Somebody has clearly got their evil eyes on his valuable research results! But neither police officers Peters and Hansen nor George's mother Fanny believe the children.