Mystery Moor isn't called by that name for nothing - as the Five are about to discover! There's something dangerous out there, and the gang mean to find out what it is, but they need some help. The travellers camped on the moor are no use - in fact, they're downright unfriendly. So the Famous Five have no other choice: they'll have to risk the treacherous mists and follow the trail . . . But do they know what they've let themselves in for?