Enid Blyton's much-loved classic series, packed full of adventure and mystery. A mysterious trip to the desolate northen isles leads to another exciting adventure for Philip, Dinah, Lucy-Ann and Jack. Bill is kidnapped, and the children are marooned far from the mainland. Will they rescue Bill in a dangerous game of hide-and-seek with an unknown enemy? First published in 1948, this edition contains the original text and is unillustrated.