No one had thought of that. Daisy stared doubtfully at Fatty. “They wouldn’t give the key to children, silly,” she said.

“They might give it to me,” said Fatty, who thought he could do anything. “Anyway I can but try. Did you happen to notice the name on the House for Sale board, Pip - I mean the name of the house-agent?”

“No. I don’t remember seeing a board.” said Pip. “But it was so foggy. We could go and find out sometime.”

“Let’s go now,” said Bets eagerly. But the others shook their heads.

“Too foggy, Bets,” said Larry. “You can’t see a thing now. It’s a good thing we all know our way home so well or we’d get lost!”

The fog was indeed very thick. It wasn’t any good doing anything that day. The Find-Outers felt a little impatient. They wanted to get on with this new mystery!

“We shall have to be jolly careful we don’t let Clear-Orf know what we’re doing,” said Larry. “We’d better try and put him on the wrong track, if we think he is snooping after us.”

“Oh yes!” said Bets. “Let’s do that. That would be fun. We could make up a mystery for him, couldn’t we? - a big robbery or something.”

“That’s not a bad idea,” said Larry. “If we could get Clear-Orf on to the track of a false mystery, he wouldn’t spend any time or attention on our real one. So, if we do find he’s snooping around, following us, or making inquiries, we’ll present him with a first-class mystery - that we’ll make up for him ourselves!”

This seemed a fine idea. It didn’t occur to any of the children to take Mr. Goon into their confidence and let him work with them. He disliked them so much, and was such a blunderer, that if any one was to be told, they preferred to tell their friend, Inspector Jenks - the “very high-up policeman” as Bets called him. He would listen to them with attention and interest, and would certainly not take any credit that was due to them. Clear-Orf, they knew, would pooh-pooh anything they did, and pretend that he had done all the brainwork.

But he was a suspicious fellow, and if he thought they really were at work on some mystery again, he would certainly try to interfere. The children felt terribly excited when they thought of this new mystery. They had so much enjoyed their first two mysteries - now here was another - and a very peculiar one too.

“Let’s see,” said Fatty, considering. “I think the first thing to do is to find out who the house-agent is, as I’ve said, and try to get the keys. Then we could explore that room and find out if possible what it’s for and why it’s fully furnished.”

“Right,” said Larry. “You can tackle the house-agent tomorrow, then. You’re good at that sort of thing. But if you manage to get the keys out of him, I’ll be surprised!”

“You wait and see,” said Fatty, who now had such a high opinion of himself that he thought nothing was impossible. He could already see himself at the head of all the British Police, the most famous solver of mysteries the world had ever known.

Nobody seemed to want to play a game. The thought of the new mystery made them feel unsettled and excited.

“Do you think it will be a dangerous mystery?” asked Bets rather anxiously. “The other two we did weren’t dangerous. I don’t think I’d like a dangerous mystery.”

“Well, if it is dangerous, we three boys will tackle it,” said Fatty rather pompously. “And you two girls must keep out of it.”

“I certainly shan’t!” said Daisy indignantly. “Bets can do as she likes - but I’m sharing this mystery from the beginning to the end, Fatty. I’m as good as you boys any day.”

“All right, all right,” said Fatty. “Keep your hair on. Good! - there’s the bell for tea. I’m frightfully hungry.”

“You always are,” said Daisy, still feeling cross.

But at the sight of the fine tea Mrs. Trotteville had provided, not one of them had any feelings but pleasure. A good tea - and a first-class mystery waiting to be solved. What could be nicer?

It was decided that all the Find-Outers should meet next day and walk to Milton House, to see the house-agent’s board.

“We could also do a bit of snooping round,” said Daisy. “I want to climb that tree, for one thing!”

“Well, we mustn’t let Clear-Orf see us doing it,” said Pip. “That would give the game away.”

“As soon as we’ve got the name of the house-agent we’ll let Fatty go and do his stuff,” said Larry. “We could wait at the house till he comes back. Then we could use the keys he brings, and go in.”

This seemed a good plan. They all hoped that the fog would clear away the next day, otherwise their parents might not let them go walking away from the roads they knew well. Milton House lay over the hill, rather off the usual track. Beyond it lay the open country, and big empty fields stretched away for miles.

The day was fine and sunny. Every one rejoiced. Now they could certainly go to Milton House. They set off soon after breakfast, joining up at different corners. Buster went with them, of course, and walked along more solemnly than usual, just as if he knew a mystery was somewhere near.

They walked over the hill, and made their way down the rather secluded lane to Milton House. It was the last house, and stood well back in its own overgrown grounds. It was plain that no gardener had worked there for years. It looked a lonely and desolate place. The house itself was large, high, and rambling, and had two or three absurd little towers.

“Well, there it is - our Mystery House,” said Pip, as they stood and looked at it from the drive. “Now wouldn’t you say that house was completely empty and unlived in? And yet there’s a furnished room at the top of it, where some one must come and live at times!”

The children felt a little shiver go down their backs. It was exciting. Probably no one but themselves and the one who furnished the room knew about that secret.

“Well - let’s take down the house-agent’s name and address,” said Fatty. “Any one seen the board?”

Nobody had. And what was more, there didn’t appear to be one to see. Other empty houses they had passed on their way all had at least one, if not two boards up, with the notice “For Sale. Apply to -” on them. But Milton House didn’t seem to have a board at all.

“But surely it’s for sale?” said Larry, puzzled, when they had made quite certain that there was no For Sale board. “Surely all empty houses are for sale or to be let? The owner wouldn’t want them to stand empty, gradually falling into ruin.”

“Well - it’s funny,” said Fatty. “I can’t understand it either.”

“It’s not much use you going to any house-agent now and asking for the keys,” said Daisy. “If no one is selling it, there won’t be any keys to get.”

“Blow!” said Fatty, upset to find his plans coming to a full stop. He thought for a minute. “Well, I’ll tell you what I could do - I could go to the biggest house-agent’s in the village, and ask about houses for sale and mention Milton House. I could see if he says anything interesting.”

“Yes - you could do that,” said Daisy. “You’d better be the one to do it, anyway. You’ve got cheek enough for anything, and you can be more grown-up than any of us. You could pretend you were asking for your mother or your aunt.”

“Yes,” said Fatty. “I think I can manage it all right, without arousing the house-agent’s suspicions. But before I go, let’s snoop round a bit. And I want to climb that tree too, and look into that room.”

“Had we better post a guard to look out in case any one comes?” said Pip. “We don’t want to be caught on somebody else’s property. Bets, you keep guard.”

“No!” said Bets, indignant at being left out of the exploring. “You keep guard youself, Pip.”

“Buster can keep guard,” said Fatty. “Here, Buster, stand at the gate and bark if anyone comes!”