He paused at that, and looked searchingly and meaningly at Marshall Allerdyke before he continued.  And Allerdyke looked back with the same intentness and nodded.

“Yes—­yes!” he said.  “If you only knew—?  Say it, doctor!”

“If I only knew if there was any reason why any person wished to take this man’s life,” responded Dr. Orwin, slowly and deliberately.  “If I knew that somebody wanted to get him out of the way, for instance—­”

Allerdyke jumped to his feet and tapped Fullaway on the shoulder.

“Come in here a minute,” he said, motioning towards the door of his bedroom.  “Excuse us, doctor—­I want to have a word with this gentleman.  Look here,” he continued, when he had led the American into the bedroom and had closed the door.  “You hear what he says?  Shall we tell him?  Or shall we keep it all dark for a while?  Which—­what?”

“Tell him under promise of secrecy,” replied Fullaway after a moment’s consideration.  “Medical men are all right—­yes, tell him.  He may suggest something.  And I’m inclined to think his theory is correct, eh?”

“Correct!” exclaimed Allerdyke, with a grim laugh.  “You bet it’s correct!  Come on, then—­we’ll tell him all.  Now, doctor,” he went on, leading the way back into the sitting-room, “we’re going to give you our confidence.  You’ll treat it as a strict confidence, a secret between us, for the present.  The truth is that when my cousin came to this hotel last night he was in possession—­that is, we have the very strongest grounds for believing him to have been in possession—­of certain extremely valuable property—–­jewels worth a large amount—­which he was carrying, safeguarding, from a lady in Russia to this gentleman in London.  When I searched his body and luggage, these valuables were missing.  Mr. Fullaway and myself haven’t the least doubt that he was robbed.  So your theory—­eh?”

Dr. Orwin had listened to this with deep attention, and he now put two quick questions.

“The value of these things was great?”

“Relatively, very great,” answered Allerdyke.

“Enough to engage, the attention of a clever gang of thieves?”

“Quite!”

“Then,” said the doctor, “I am quite of opinion that my ideas are correct.  These, people probably tracked your cousin to this place, contrived to administer a subtle and deadly poison to him last night, and entered his room after the time at which they knew it would take effect.  Have you any clue—­even a slight one?”

“Only this,” answered Allerdyke, and proceeded to narrate the story of the shoe-buckle, adding Fullaway’s theory to it.  “That’s not much, eh?”