"You said that three times. Nobody is going to ask you to come here at night unless you come to watch one of the others, and it was your own idea to get them to work for you, wasn't it?... Now, let's be sensible. The map showed four tracks meeting here, and the path we've just used was one of them. This must have been a splendid place for a smuggler to hide treasure if he wanted to get rid of it quickly. It would be easy to defend, too, if it were attacked, and I believe there's a good chance that something is hidden here."

For the next hour they explored the walls from the outside. They looked to see if any of the great stones within their reach were loose or whether any showed strange markings or signs. They searched, too, along the ground at the foot of the walls, and once Jon went down on his hands and knees and scraped the sand from a bare patch in the hope that he might find a trap-door.

They found an ideal picnic place inside the castle on the top of a high grassy bank that rose, in one place, to within two feet of a part of the outer wall that faced due south. Here they were almost as high as the sentinels who once would have paced the ramparts on the look-out for invaders. They were sheltered here from the wind that sang among the broken stonework, and Penny flopped down and stretched herself on the sweet-smelling turf which was gay with tiny nodding scabious and little red and yellow blooms of Lady's Slipper.

She sniffed rapturously. "It's lovely!" she sighed.

Jon was already unpacking the haversack. "What's lovely? Can you smell meat pie?"

"No, I didn't mean that. I meant everything. I love the smell of the sea and the Marsh and the sheep. And I love being here in the sunshine and listening to the birds, and I love the Dolphin and the fun we're going to have, and today is one of the days when I feel I never want to go back to school again."

"You'd better have something to eat," her cousin said rudely. "You can't be feeling well... As soon as we've finished we'll do as I said and write down all the things we know about the Ballinger and Slinky."

A quarter of an hour later, when they were ready to talk again, Jon brought out his notebook and pencil and began his task.