The Enid Blyton Adventure Series

When they discover their guardian is sick, Jack and Lucy-Ann accept Philip's offer to spend the rest of the holiday at his new cliff top home in Cornwall. There they meet Joe, a friendly man who helps Philip's widowed mother Allison, at her Art Gallery, and Philip's sister, Dinah. But as they leave they are followed by a stranger.

After finding an old smugglers' tunnel while exploring, the boys fall into it and are unable to climb out. When they follow the length of the tunnel they discover stairs which lead to Craggy Tops' cellar. After Allison is befriended by the mysterious stranger, BIll, he offers to take the children out for a boat trip. But they don't trust him and set about trying to discover his true motives.

The day after their boat trip, the children 'borrow' Joe's boat and re-trace the route BIll took the previous day to the Island of Gloom. While there, Kiki accidentally leads them to a disused mine shaft. But while exploring, the children discover Jake and two workers printing counterfeit notes and Jack is caught and taken prisoner. Will he escape?

The holidays are drawing to a close. Jack and Lucy-Ann have to return to their Uncle, but they don't want to go. The children decide to camp in the garden. Jack hears the call of an owl and persuades the others to go with him into the woods to see it. But while searching for the owl, they discover the broken wall of Woods Castle and see strange flickering and hear noises in the undergrowth.

After Bill arrives, Dinah questions what he really does for a living, suspecting that he might be a secret agent. The children slip away to look at the Castle again. But this time they are chased by an unseen malevolent force. In their panic to escape, Kiki gets lost and Jack refuses to leave her. Unknown to the children, Kiki has been captured by a disturbed young man.

After Philip seeks the help of Bill and Allison, the children find their way through a turret window and continue their search for Kiki. But they soon discover that something strange is going on in this castle. And they are determined to find the answer to so many mysterious questions.