The Portuguese smiled sheepishly, walked to the wall and gripped the handle. Evidently the point had embedded in a lath, for the knife did not move. He pulled again, exerting all his strength and this time succeeded in extracting not only the knife but a large portion of the plaster and a strip of the wallpaper.
"You fool!" said the colonel angrily, "see what you have done—Jumping Moses!"
He walked to the wall and stared, for the dislodgment of plaster and paper had revealed three round black discs, set flush with the plaster and only separated from the room by the wallpaper, which had been stripped.
"Jumping Moses!" said the colonel softly. "Detectaphones!"
He took Pinto's knife from his hand and prised one of the discs loose. It was attached to a wire which was embedded in the plaster and this the colonel severed with a stroke of the knife.
"This is the business end of a microphone," he said.
"The voice!" gasped Pinto, and the colonel nodded.
"Of course. I was mad not to guess that," he said. "That's how he heard and that's how he spoke. Now, we're going to get to the bottom of this."
With a knife he slashed the plaster and exposed three wires that led straight downward and apparently through the floor. The colonel rested and eyed the debris thoughtfully.
"What is under this flat? Lee's office, isn't it? Of course, Lee's!" he said. "I'm the fool!"