"Let's think about the smell of turps on that cat's tail." he said.
"You said turps was used to get paint-brushes clean, or to get smears of paint off anything," said Bets, drying her eyes. "Do you suppose the cat had got against some wet paint or something, and the paint was cleaned off with turps?"
Fatty stared at her. Then he leapt to his feet with a yell, and smacked the summer-house table hard with his hand. His face went very red.
"What's up?" said Larry in alarm. "Have you sat on a wasp or something?"
"Listen," said Fatty, sitting down again, looking terribly excited. "Young Bets has got hold of the right idea. Turps was used to get paint off that cat's tail. And how did the paint get there, and what colour was it? Well, we know the colour, because we've got the tin of paint that was used, and we've got a stone with a blob of that same paint on it — it was creamy-brown."
The others stared at him. Fatty got the tin out from behind the loose board and opened it. He dipped the brush into the tin and then dabbed it on the dark-brown summer-house table.
"Look at that," he said. "See that creamy patch? Well, that's what must have been on the cat's tail — in the middle of it — creamy-brown paint! And now, I ask you, what other cat has a patch of creamy-brown hairs on her tail?"
"Dark Queen!" said everyone at once. Eyes gleamed, and faces grew red with excitement as the five children worked out all that the turps and the paint meant
"Yes," said Fatty. "And that cat whose tail smelt of turps must have had a ring of hairs in her dark tail painted a light colour, so that she might be mistaken for Dark Queen, and then the paint on her tail was rubbed off with strong turps — that's why the cage smelt of turps both times. It was done both times."
"Golly!" said Larry. "This is frightfully exciting. Somebody made a very clever plan. Let me see! I suppose Dark Queen was stolen away in the morning, and the other cat's tail painted to make her seem as if she was Dark Queen — everyone knew Dark Queen had a ring of paler hairs in her tail where she had been bitten."