"I don't know," said Fatty. "It must mean something. I hope it's not in a secret code."
"What's a secret code?" asked Bets.
"Oh, a way of writing messages so that only the persons receiving them know what they mean," said Fatty. "But somehow I don't think this is a code. After all, that old man had got to read it and understand it, and I'm quite sure he hasn't brains enough to understand a code."
"Then could there be another message, but written in secret ink?" said Pip suddenly. "You know how you taught us to write secret messages, in between the lines of an ordinary letter, don't you, Fatty? Well, could there be a message written between these lines, in secret ink?"
"Yes, there could," said Fatty. "And that's what I think we shall find I Good for you, Pip. Can you go and get a warm iron? If we run it over the paper, the secret message will show up."
Pip ran off. Gladys was actually ironing in the kitchen, and though she was very surprised to think that Pip should want to borrow the warm iron to take into the garden for a minute, she let him. He came tearing up to the summer-house with it in his hand.
"I've got it!" he said. "Here you are. Put the paper out flat on the wooden table. That's right. Now I'll run the iron over it."
He ran the warm iron over the spread-out bit of paper. Then he lifted it off and looked at the message. "There's another one coming up, look—between the lines of the other!" squealed Daisy, in excitement. "Iron it again, Pip, quick! Oh, this is too thrilling for words!" Pip ironed the paper again—and this time another message showed up very clearly indeed. The words came up, looking a queer grey-brown colour, and began to fade almost as soon as the children had made them out.
"Tell Number 3. Waxworks, Tuesday, nine pm.—Number 5."
"Golly!" said Pip. "Look at that! Tell Number 3—that must be one of the gang. And Number 5 must be another."