Five on Kirrin Island Again

Five On Kirrin Island Again is the sixth novel in the Famous Five series by Enid Blyton. It was first published in October, 1947. Julian, Dick and Anne come to George's house for their holidays. They plan to explore Kirrin island a bit more. But when Uncle Quentin announces that he is going to use the island alone for a few days, the Five are surprised. They request their uncle to signal 6 times twice day, one at the morning and the other at the evening,

There exist some film versions, e.g. Fünf Freunde.