Tom and his sister, Ruth, are home from school for a holiday. They are joined by their American friends, the Wheatley twins, Jane and Boyd. The four have already planned to explore Orleigh Cave, which has a local reputation of being haunted. But they are searching for a lost treasure of the Romans which they believe to lie somewhere in the cave. After being trapped in the cave by a rock fall, they travel deeper into the cave and stumble upon and into...