'A tree has fallen on the roof at Kirrin Cottage and smashed it, right at the start of the holidays! The four children are sent away to stay with friends of Castaway Hill, with Timmy in hiding. But all is not as it seems at the old house, with its hidden passages and underground tunnels. And when not one, but two people disappear, a thrilling adventure begins. What are the secrets of Smuggler's Top, and how will they be revealed?'--Back cover.