“How did you know about my experiments?” I asked quietly.

He shrugged his shoulders.  “There are such things as trade secrets.  It is necessary for a business man to keep in touch with anything that may threaten his interests.”

I hesitated a second.  “What is it that you propose—­exactly?” I inquired.

I saw—­or thought I saw—­the faintest possible gleam of satisfaction steal into his eyes.

“I propose that you should finish your experiments as soon as possible, make some of this explosive, and hand the actual stuff and the full secret of its manufacture over to us.  In return I will guarantee you your freedom, and let you have a quarter interest in all profits we make out of your invention.”

He brought out these somewhat startling terms as coolly as though it were an every-day custom of his to do business with escaped convicts.  I bent down from the bed, and under cover of picking up my second cigarette from the tray, secured a few useful moments for considering the situation.

“I have no objection to the bargain,” I said slowly, helping myself to a match off the table; “the only question is whether it is possible to carry it out.  My experiments aren’t the kind that can be conducted in a back bedroom.  I should want a large shed of some kind, and the farther away it was from any houses the better.  There is always the chance of blowing oneself up at this sort of business, and in that case an explosive like mine would probably wreck everything within a couple of miles.”

“You shall work under any conditions you please,” said McMurtrie amiably.  “If it suits you we will fix you up a hut and some sheds down on the Thames marshes, and you can live there till the experiments are finished.”

“But I should be recognized,” I objected.  “I am bound to be recognized.  I am fairly well known as it is, and with my picture and description placarded all over England, I shouldn’t stand a dog’s chance.  However lonely a place it was, some one would be bound to see me and give me away sooner or later.”

McMurtrie shook his head.  “You may be seen,” he said, “but there is no reason why you should be recognized.”

I paused in the act of lighting my cigarette.  “What do you mean?” I asked with some curiosity.

“My dear Mr. Lyndon,” said McMurtrie, courteously, “as a scientist yourself you don’t imagine that it’s beyond the art of an intelligent surgeon to cope with a little difficulty like that?”

“But in what way?” I objected.  “A disguise?  Any one can see through a disguise except in novels.”

The doctor smiled.  “I am not suggesting a wig and a pair of spectacles,” he observed.  “It is rather too late in the world’s history for that sort of thing.”  Then he stopped and studied me for an instant attentively.  “In a fortnight, and practically without hurting you,” he added, “I can make you as safe from the police as if you were dead and buried.”