George found the iron ring in the little opening and knotted his rope in it. The end fell down the chimney to the hearth like a brown snake. George jumped down.

“Now we’ll all pull,” he said, with his slow, wide smile. So they all pulled - and the rope gave a little as the big stone above swung round and back, leaving just enough room for anyone to squeeze through.

Jack climbed up the chimney again and gave a shout as he saw the dark opening. “Oh, the secret passage is here all right! Come on, all of you!”

Poor Dimmy! She was really horrified at seeing everyone go up that dirty, sooty old chimney and getting as black as negroes - but even she went up too, just to see what kind of a secret passage it could be!

George had squeezed through the opening that was made when one big stone had swung out of its place. It had been cunningly built on a kind of swivel set in the next stone, and when weight was put on to the iron ring the stone swung round.

A very narrow way led round the back of the chimney - so narrow that George had to walk sideways to make himself small enough. Then he came to an iron ladder set at his feet, disappearing down into the darkness. He called back to the children.

“There’s a ladder here, going downwards. I reckon there’s an outer wall and an inner wall to part of this tower, and that’s where the passage is! The rest of the tower wall is solid.”

Down the narrow iron ladder they all went. They had to hold their torches in their teeth, for they needed both their hands. Dimmy had no torch, so she stood at the top of the ladder, waiting for them all to return.

The iron ladder went right down inside the wall and ended below the tower itself. A small room was at the foot of the ladder, and in it the children saw two old tops, a wooden hand-carved toy boat and some old, mildewed books.

“This must have been Dimmy’s grandfather’s hidey-hole when he was a boy,” said Jack. “Look at his toys!”

From this small underground room, smelling so musty and queer, a narrow passage led up the cliff.

“This passage can’t be so very far underground,” said George, leading the way. “Hallo! Look there! Surely that is daylight?”

It was! A bright circle of daylight shone not far above their heads.

“I guess a rabbit has made its burrow above us,” said Jack, with a laugh. “He must have burrowed from the surface down to this passage. What a shock for him when he fell through!”

“Well, the bunny has let some fresh air into this place, at any rate,” said George. “Perhaps that is what has kept it fresh enough to breathe in.”

They went along the passage, and then came to a stop. “What’s up, George? Why have you stopped?” asked Jack.

“Because the passage has fallen in here,” said George. “We’ll have to get spades and dig it free again. The roof has fallen in, and we can’t get any farther. We’ll come back and dig it out. I reckon the passage goes on to the tower of the Old House, and then we’ll find an iron ladder going up inside the walls just as we found at Peep-Hole.”

The children squeezed back through the passage and went up the iron ladder to the chimney. Dimmy had got down again and was waiting for them in the girls’ room, having washed herself clean.

They told her excitedly what they had found. Jack ran down to the shed to get spades, and to find some biscuits for himself, for he had had no dinner.

“We shall be able to rescue Mike and Paul very soon now,” said Peggy hopefully.

“Better clear the passage now and try to get to the boys to-night,” said George thoughtfully. “You see, if we can rescue them at night there’s not so much fear of us being heard, and we can get a good few hours’ start of the folk at the Old House.”

“Right, George,” said Dimmy, who was just as excited as the children.

George and Jack went to clear the passage ready for the night’s adventure. The girls went to wash themselves, and to pore once more over the exciting diary that had told them just what they wanted to know.

In an hour’s time Jack and George came back, hot, dusty, sooty, and thirsty. Dimmy made them have a bath, and put on clean clothes - though George looked very comical in Mike’s shorts and jersey! Then they all sat down to a good tea, which they really felt they had earned.

“This is getting more and more exciting!” said Peggy, spreading her bread and butter with Dimmy’s homemade shrimp paste. “I feel as if I’m bursting with excitement. If only old Mike knew what we were doing!”

“He’ll know soon enough,” said Jack, with his mouth full.

“I reckon the queer folk up at the Old House will be pretty furious when they find Mike and the prince gone,” said George rather solemnly. “I think you’d better all get away from here with Paul, whilst Miss Dimity and I tell the police and find out a bit more about this prince of yours.”

“Get away from here?” said Jack. “But where could we go that was safe?”

No sooner had he said it than he and the girls had the most marvellous idea in the world.

“Our secret island! We’d be safe there! It’s not far from here!” yelled Jack.

“The secret island!” cried Peggy and Nora.

“What’s that?” asked George in astonishment.

“It’s on Lake Wildwater, about forty miles from here,” said Jack. “We lived on our secret island on the lake when we ran away once - it would be a wonderful place for the prince till he’s safe from his enemies.”

“Good idea!” said George. “I’ll take you round the coast in my boat to Longrigg, where I’ve a brother who has a car. He can drive you to Wildwater - and you can do the rest!”

“Won’t Mike be pleased, won’t Mike be pleased!” shouted Nora. “Oh, I do feel so happy!” And she danced poor Dimmy round and round the room till Dimmy had to beg for mercy!

It was arranged that Mike and Paul should be rescued that night through the secret passage - if only the entrance at the other end could be used and was not too old or stiff!

“Jack and I went right along the passage to the Old House tower,” said George. “There’s an iron ladder there like ours. I reckon it leads up to the top room, to the fireplace.”

“We had better plan everything carefully,” said Dimmy. “George and Jack had better rescue the boys, and bring them safely back here. Then I and the girls will prepare plenty of food and take it down to George’s boat. We will wait there for you.”

“Yes, we shall need plenty of food on the secret island,” said Nora. “There are wild raspberries there, and wild strawberries, but that’s about all, unless we catch rabbits and fish as we did last year when we lived there!”

“You’ll only be there a day or two until we can find out about Prince Paul and get someone to take charge of him till he goes back to his own land,” said Dimmy. “I will stay behind here - and George will return to me, too, so that I shall be able to deal with the folk at the Old House. I shall simply say that you have all gone away.”

“Dimmy, let’s get the food ready for to-night,” said Peggy eagerly. “We only need food - we don’t need saucepans or kettles, or beds or anything like that - everything is neatly stored away in the dry caves on the secret island, ready for when we went there again. But we shall need plenty of food for five people.”

So the two girls and Dimmy began to pack up all kinds of food. There was a joint of meat, two dozen tarts, a tin of cakes of all kinds, a tin of biscuits, some tins of soup and fruit, potatoes and peas from the garden, and a basket of ripe plums. Cocoa was put into the box of food, and tins of milk. Nora remembered the sugar, and Peggy thought of the salt. It was really exciting packing everything up.

George carried the big box down to the boat and stowed it there. Jack followed with two baskets. Dimmy hurriedly stuffed a box of black currant lozenges into one basket, in case any of them caught cold that night.