“Golly! How did you do it?” asked Larry, in the greatest surprise.
“I knew you would!” squealed Bets.
“How did you do it?” asked Pip and Daisy, burning with curiosity. “Go on - tell us.”
“It’s easy,” said Fatty, smoothing back his tidy hair. “Too easy for words.”
“Don’t keep on saying that! Tell us how you did it!” said Larry. “It’s extraordinary.”
“Well, come up and I’ll show you,” said Fatty. “As a matter of fact, it’s a thing all detectives ought to jolly well know. Elementary.”
“What’s elementary?” asked Bets, climbing the stairs behind Fatty.
“What I’ve just said - too easy for words,” said Fatty. “Well, here we are. Now, Larry, you lock us all four into the room - Buster too, if you like, or he’ll scratch the door down - and then you can all watch what I do. I tell you, it’s elementary!”
The three who were locked in with Fatty watched in excitement. They saw the door shut. They heard Larry turn the key in the lock. They each tried the door. Yes, it was locked all right.
“Now watch,” said Fatty. He took a folded newspaper from his pocket and unfolded it. He flattened the big, wide double-sheet. Then, to the children’s surprise, he slid the newspaper under the bottom of the door until only a small piece was left his side.