Julian, Dick, Anne, George and Timmy the dog go to stay at a Coastal farm in Cornwall. When they arrive they see a boy on the rocks and believe he is swept away by the incoming tide. Julian and Dick attempt a rescue while George and Anne arrive at the Farm only to discover that the boy Yan is there having his tea. Julian Dick are not pleased when they arrive to discover they got wet for nothing.
A travelling show arrives in at the farm and promises to put on a show in excahnged for being aloowed to stay for the night. The leader named the Guv'nor introduces the Five to Clopper the Pantomine horse who is part of the show.
Yan tells the Five tales of the wreckers who would confuse boats with lights and make them crash on the rocks and steal their loot. When lights again start to shine the Five investigate and see Mr Penruthlan from the farm and believe he is a smuggler but it turns out he's really a Policeman trying to catch the Smugglers.
After the Travellers put on their show it is clear that they are the true thieves and the Five have to catch them.