Geoffrey naturally became indignant, but in the taxi the detective put his hand into the inner pocket of the young fellow’s dinner-jacket and drew forth the missing wallet!

“See!” exclaimed the man; “here is the missing property—found upon you! You can’t make any excuse, can you?” Then turning to Owen he said: “It’s very fortunate, sir, that you came to Vine Street at once—or he would have thrown the case away.”

Geoffrey could not utter a word. He knew that he was the victim of some foul plot, from which it seemed impossible to extricate himself.

Back at Half Moon Street, a prisoner in the hands of the police, he stood with the three men, utterly dumbfounded. He protested that the wallet must have been purposely placed in his pocket when he had taken off his jacket in order to wash his hands. But all three laughed at this lame explanation.

“And what do you intend to do?” asked Falconer.

“To prosecute you for theft,” answered Owen. “And it will be a nice end to your very promising career as a wireless engineer!”

Geoffrey bit his lip in dismay.

“Is there no other way out of it?” he asked in a low, hard voice.

“Yes,” answered Paget, “there is.” And he asked the detective to retire into the next room. Then when the door was closed, the man Paget exclaimed:

“I propose, Owen, that if this young fellow gives us the diagrams of his new device for printing automatic wireless signals from the call-device, that we say nothing about it. It would only be a quid pro quo—eh?”