“How funny! I can smell oranges too now!” he said.
Bets suddenly snatched the letter from him, her eyes bright. She held it to her nose.
“This is what smells of oranges!” she said excitedly. “Smell it, all of you.”
They smelt it. Yes, it smelt of oranges - and that could only mean one thing. Fatty had written another letter on the same sheet - in orange juice, for secret ink!
Bets sat down suddenly because her knees began shaking.
“I’ve got that feeling again,” she said earnestly. “You know - that something is wrong with Fatty. Let’s test the letter quickly for secret writing.”
Daisy flew down to get a warm iron. It seemed ages to wait whilst it got hot enough. Then Pip deftly ran the warm iron over the letter.
At once the secret message came up, faintly brown. The children read it with beating hearts:
“DEAR FIND-OUTERS - Don’t take any notice of the visible letter. I’m a prisoner here. There’s some very dirty work going on; I don’t quite know what. Get hold of Inspector Jenks AT ONCE and tell him everything. He’ll know what to do. Don’t you come near the place, any of you. - Yours ever, ‘FATTY.’ ”
There was a silence. The Find-Outers looked solemnly at one another. Suddenly their mystery seemed to be very deep and dark and dangerous. Fatty was a prisoner! Why had he written that other letter in ink?