"How?" said Pip, rather scornfully.

"Well, we could go and hunt about next door to find where the bottle of turps is kept or something like that," said Bets. "I don't say it will help; but after all, if it's a clue, we might find out something."

"Bets is right," said Fatty. "She really is. We did smell turps both times — and of course we ought to go and look to see if we can find where it's kept. Who knows, we might fine other clues then!"

"Let's go now, then," said Pip. "No time like the present! Come on. Look out for Tupping though. He won't like us snooping about."

They all went over the wall again, leaving poor Buster in the shed. They sent Pip into the garden to see whereabouts Tupping was.

Pip came back and reported that he was tying up something near the house. "So we're safe for a bit," he said. "Come on. Let's sniff in the cage again, and see if the smell is still there. Then we'll go hunting for the stuff."

They all sniffed in the cage. The faint smell of turps still hung there. Miss Harmer came up as the children were sniffing. She did not seem very pleased to see them.

"I don't want anyone near the cat-house now," she said. "This disappearing of Dark Queen twice running is getting on my nerves. I'd rather you kept away, children."

"Miss Harmer, do you use turps to clean out the cages at all?" asked Fatty.

Miss Manner looked surprised. "Of course not," she said. "I use an ordinary disinfectant. Cats hate the smell of turpentine,"

"Well, how did the smell of turps get into the cage then?" said Larry. "You sniff, Miss Harmer, and see if you can smell it."

But Miss Harmer had not got a very good nose for smelling, and she did not think she could smell anything like turps in the cage.

"Didn't you yesterday when you went in and found Dark Queen was gone?" said Larry.

"Well, perhaps I did," said Miss Harmer, trying to remember. "But I couldn't swear to it. I was so upset at Dark Queen disappearing again."

The children peered into the cage, still sniffing. Miss Harmer sent them off. "Do go," she said. "I really feel nervous now when anyone comes near the cats."

"Let's go to the shed and see if we can find any turps there," said Fatty. So they left the cat-house and went off to the two sheds that leaned back to back, not far from the greenhouses.

"You girls take one shed and search it and we boys will take the other," said Fatty.

So they all began to hunt hard in the two sheds, but there was no turps to be found anywhere.

Larry saw Luke passing by, looking very gloomy indeed. He whistled to him.

"Hie, Luke! You look as if you had lost a shilling and found sixpence. Cheer up!"

"You wouldn't feel very cheerful if you felt as frit as I do," said poor Luke.

"What you doing in them sheds?" he said. "You'll catch it if Mr. Tupping comes along and sees you messing about there."

"We're looking for the turpentine," said Fatty, poking his round face out of the shed. Luke looked astonished.

"Turps?" he said. "What do you want turps for? It's kept in the other shed — on the shelf — I'll show you. But what do you want it for?"

Luke led the boys into the other shed, where Daisy and Bets were. He pointed to a shelf on which various bottles and tins stood. "It's there somewhere," he said.

The children looked. They picked up one bottle after another and sniffed it. But there was no turpentine at all.

"We've already looked, anyway," said Daisy.

Luke was puzzled. "It was there," he said. "I saw it myself yesterday. Where's it gone?"

Fatty began to feel excited, though he didn't quite know why.

"We've got to find that bottle," he said.

"Why?" asked Daisy.

"Don't know," said Fatty. "But we've got to. It's gone. Maybe it's been hidden away. We've got to find it."

"I bet old Buster could find it for us," said Fatty.

Luke went off to his work, still looking extremely gloomy. The others went to the wall. Pip and Fatty climbed over it and dropped down to the other side. Pip went to the garden-shed at the top of the garden, and found a small jar of turps.

Fatty opened the bicycle shed and let out Buster, who tore round and round him, barking as if he had not seen Fatty for at least five years.

"Come on, Buster," said Fatty, picking him up. "You've got to do a little work."

In a short time Fatty, Buster, and Pip were over the wall with the others.

"The coast is all clear at the moment," said Larry.

Fatty shook some turps on to his rather grubby hanky, and held it to Buster's nose. "Smell that, old fellow. Smell it good and hard. That's turps. Now, you just run all over the place and see if you can find the same smell again. Good old bloodhound, aren't you?"

Buster did not like the smell of the turps at all. He looked away from the hanky with a face showing intense disgust. Then he sneezed violently three times.

"Go on, Buster dog, find it, find it!" said Fatty, flapping the hanky at him. Buster looked up at Fatty. He knew quite well what "find it" meant. He was always finding things for Fatty. He trotted off, his pink tongue hanging out, his tail in the air.

"He's looking for rabbits, not turps," said Larry in disgust. "Look — he's found a rabbit-hole — and now we shan't be able to make him see sense for ages!"

Buster had found a hole. It was in a bank. He stuck his nose into it, gave a whine, and began to dig hard in his usual way, sending the earth flying out behind him.

"Come out, idiot," said Fatty. "I didn't say rabbits, I said turps."

Fatty pulled Buster out by his hind legs. Something rolled out behind the little dog. All the children stared at it. It was a cork. Fatty picked it up and smelt it.

"It smells of turps!" he said in excitement, and the others crowded round to smell it. It did. There was no doubt about it at all.

In a trice Fatty was down on his hands and knees, feeling in the hole.

He pulled out a bottle. On it was an old label, half-torn, but the letters "turp" could still be faintly seen. There was still a little turpentine in the bottle, too.

"Here's what were were looking for," said Fatty triumphantly. He showed the bottle to the others. Bets went to the hole and peered in out of curiosity.

"There's something else, Fatty," she cried in excitement, and put in her hand. She pulled out a tin. The others crowded round again to look, feeling very thrilled.

"What is it?" said Larry eagerly. "A tin of paint. Here's a knife. Let me prise off the lid."

He did so — and the children saw that the tin was nearly full of a light-brown paint.

"How queer!" said Fatty. "It's the colour of that blob of paint on the stone we found. Look!"

He compared the stone with the paint in the tin. It exactly matched.

"Now," said Fatty, in glee, looking at the turps and the tin of paint, "now — who put the paint and turps down that hole — and WHY?"