This text details the adventures of four children, a boy named Jock, and Timmy the dog as they investigate mysterious occurrences on a lonely moorland. While camping under the loose supervision of Mr. Luffy, the group becomes fascinated by legends of "spook-trains" appearing at a nearby abandoned railway yard. Their curiosity leads to the discovery of a criminal smuggling operation that uses a hidden, bricked-up tunnel section to store black-market goods transported by an old steam engine. The children are briefly captured by the smugglers, including Jock's stepfather, but they eventually escape and help the authorities dismantle the ring. Through teamwork and bravery, they transform a frightening local ghost story into a successful rescue and police investigation.