'Up on the moor they went in the thick mist... And they never came back,' he said. 'Never heard of again!' This holiday, the Famous Five are determined to uncover the secrets of Mystery Moor from years ago. But they soon learn there's an even bigger mystery to solve - and it's happening now! Why is a plane circling the treacherous moor in the middle of the night - and what is it delivering? One thing is for sure - it's something suspicious.