Dinner-time came. Peggy went up to fetch Jack. He was huddled in a corner with his magnifying-glass, trying to read every word of the old, old diary.

“Dinner-time,” said Peggy. “Have you found anything interesting, Jack?”

“No,” said Jack. “It’s all about how he goes birds’-nesting and fishing and boating. He must have been a nice sort of boy. He was a great one for playing tricks on people too. It says here how he put a toad into his aunt’s bed, and she woke the whole house up to get it out!”

“Naughty boy!” said Peggy. “And poor old toad! It must have hated being squashed under the bedclothes. What else does it say?”

“Oh, lots of things,” said Jack, flicking over the pages. “Tell Dimmy I’ll be down in half a minute. I just want to finish the next few pages.”

So Peggy went downstairs again, and Dimmy and the two girls began their meal without Jack. They were in the middle of it when they heard a tremendous shouting, and Jack’s feet came tearing down the stone staircase. The door into the kitchen was flung open, and then the dining-room door flew back with a crash. The girls almost jumped out of their skin. Dimmy leapt to her feet.

“Whatever’s the matter?” she cried.

“I’ve found it, I’ve found it!” yelled Jack, dancing round the room like a clown in a circus. “It’s all here - there’s a map of it and everything!”

The girls squealed. Dimmy sank down into her chair again. She wasn’t used to these adventures!

“Show! Show us the map!” yelled Nora. She swept aside her plate and glass with a crash, and Jack set the old diary down on the tablecloth.

“Listen,” he said. “This is Dimmy’s grandfather’s entry for the third of June, exactly one hundred years ago! He says, ‘To-day has been the most exciting day of my life. I found at last the old hidden passage between Peep-Hole and the Old House tower. A gull fell into the chimney of my room and I climbed up it to free the bird. Whilst I was there I pressed by accident on the great stone that swings round to open the passage in the wall of the tower.’ ”

“O-o-oh!” squealed Nora. “We can find it too!”

“Don’t interrupt,” said Peggy, her face pale with excitement. “Go on, Jack.”

“He goes on to tell how he got into the passage, which runs down the walls of our tower to the ground, up the cliff to the Old House, branches off to join our own secret passage somewhere, and also goes on to the tower of the Old House, up and inside the thick walls there, and into the topmost room of the tower!” Jack could hardly speak, he was so thrilled at having found what he wanted.

“There’s a rough map here that he drew after he had found out all about the passage. He kept the secret to himself, because he was afraid that if he didn’t his father might have the passage blocked up.”

Everyone pored over the map. It was faded and difficult to see, even under the magnifying-glass, but the children could plainly follow the passage from their tower, downwards in the wall right to the ground and below it, then underground to the Old House, up through the thick walls there, and into the top room of the Old House tower.

“I knew I was right! I knew I was right!” said Dimmy, quite as excited as the children.

“Let’s go straight up and find it!” said Nora. “Come on! Oh, do come on!”

They all fled upstairs, tumbling over the steps in their haste. They must find that secret door in the chimney. Quick! Quick!

They all rushed into Jack’s bedroom at the top of the tower - but at the first look round Peggy gave a cry. “What sillies we are! There’s no fireplace here!”

“Goodness - of course not,” said Jack in dismay. “I’d completely forgotten that. But the map quite clearly shows that the passage starts somewhere in the chimney.”

“Our room below has a big stone fireplace!” cried Nora. “It must be there that the passage starts. Hurry!”

Down they tore to Nora’s room, where there was certainly a big, old-fashioned stone fireplace. Jack looked up it.

“Get me a stool or something,” he said. “I can stand on that and grope about.”

So, with the girls jigging impatiently about below, Jack stood on a stool and groped about in the dirty old chimney. At one side he felt what seemed to him to be narrow steps cut in the chimney. He told Miss Dimmy, looking down at her as black as a little sweep!

“Yes, that’s right, there would be steps there,” said Dimmy. “In the olden days small boys were sent up to sweep these big chimneys and sometimes steps were cut to help them. Can you get up them, Jack?”

Jack thought he could. So up he went, choking over the years-old soot. The steps were very small, and came unexpectedly to a little opening off the chimney itself. Jack was sure that the door to the hidden passage was somewhere in that opening!

The stones and bricks were intermixed there and were rough to his hand. He pulled and pushed at each one, hoping it would swing round and show him an opening beyond. But not until he suddenly slipped and bumped against a certain stone did anything move at all!

His shoulder fell against a stone that stood out from the rest. It gave under his weight, and seemed to swing round, giving a click as it did so. Jack quickly shone his torch on to it, and saw a small hole appearing in the wall of the chimney. He put his hand into the hole and felt an iron ring.

“I’ve found the entrance! I’ve found it!” he yelled down the chimney. He pulled hard at the iron ring, and felt the stone to which it was fastened move a little; but no matter how hard Jack pulled he could not make the stone move any farther.

He climbed down the chimney, and the girls cried out in horror when they saw his black face and hands. He grinned at them, and his teeth shone white in his mouth.

“Dimmy, we’ll have to get George to help us,” he said. “I think the entrance-stone is stiff with the years that have gone by since it was last used. If we got George to bring a thick rope and fasten it to the iron ring I’ve found up there, we could swing the stone round all right and see the entrance to the passage. The stone has moved just a little - I can see the crack with my torch where it should come away from its place.”

“George is working in the garden this afternoon,” said Dimmy joyfully. “We can get him easily. No, Jack, no, don’t you go and get him - you look so awful!”

But Jack was gone. He sped down the staircase and out into the garden. George was busy digging up potatoes. Jack burst on him, crying, “George, George, come quickly!”

George looked up in surprise, and saw a black, grinning creature running towards him. He got a tremendous shock and dropped his spade. It took him quite a minute before he would believe that the black creature was his friend Jack!

Talking eagerly and telling George things that astonished the farm-lad greatly, Jack led him up the stone staircase to the girls’ bedroom.

“Has he brought a rope?” cried Nora.

George nearly always had a rope tied two or three times round his waist. He gaped at the two girls and Miss Dimmy, and then said, “Where’s Mike?”

“You haven’t been listening!” said Jack impatiently. “I was telling you all the way up.”

“Let me tell him,” said Dimmy, seeing that George really was thinking that everyone was quite mad. So she told him the whole story as shortly as possible. George nodded his head solemnly every now and again. He didn’t really seem astonished now that he knew everything, but his eyes gleamed when he heard that Dimmy wanted him to go up the chimney and tie his rope to the iron ring.

“I’d like to get Mike back all right,” said George, undoing the rope round his middle. It proved to be very long and very strong. He disappeared into the chimney with Jack’s torch. Jack tried to climb up after him, he was so impatient, but came down at once, his eyes and mouth full of soot kicked down by George’s enormous boots.