"I can't understand Marion; she is so very mysterious over it all. Each time I've seen her I've tried to get the truth from her, but all in vain," Rolfe declared. "My own idea is that on the night in question, when they went together to Queen's Hall, Maud told Marion something-- something that is a secret."

Max pondered. His friend's explanation tallied exactly with his own theories; but the point still remained whether or not there had been foul play.

"But why doesn't the Doctor send me word of his own safety?" asked Barclay. "I was with him only a few hours before, smoking and chatting.

He surely knew then of his impending flight. It had all been most ingeniously and cleverly arranged."

"No doubt. When I knew of it I was absolutely staggered," Rolfe said.

It was curious, thought his friend, that he did not admit visiting the house after the furniture had been removed.

"I thought you left at nine that night to go to Belgrade. Marion told me you had gone," Max remarked.

"Yes. I had intended to go, but I unfortunately missed my train. The next day the old gentleman sent somebody else, as he wanted me at home to look after affairs up in Glasgow."

"And how did you first know of Maud's disappearance?" asked Max, thinking to upset his calm demeanour.

"I called at the house," he replied, vouchsafing no further fact.

"And after that?" Max inquired, recollecting that tell-tale stain upon the woman's bodice.

"I made inquiries in a number of likely quarters, without result."

"And what's your theory?" Max asked, looking him straight in the face, now undecided whether he was lying or not.

"Theory? Well, my dear fellow, I haven't any. I'd like to hear yours.

The doctor and his daughter have suddenly disappeared, as though the earth has swallowed them, and they've not left the least trace behind.

What do you believe the real truth to be?"

"At present I'm unable to form any actual theory," his friend replied.

"There has either been foul play, or else they are in hiding because of some act of political vengeance which they fear. That not a word has come from either tends to support the theory of foul play. Yet if there has been a secret tragedy, why should the furniture have been made to disappear as well as themselves?" Then, after a pause, he fixed his eyes suspiciously upon Charlie, and added, "I wonder if the Doctor kept any valuables or securities that thieves might covet in his house?"

Rolfe shrugged his shoulders. Mention of that point in no way disturbed him.

"I have never heard Maud speak of her father having any valuable possessions there," he said simply.

"But he may have done so, and a theft may have been committed!"

"Of course. But the whole affair from beginning to end is most puzzling. I wonder the papers didn't get hold of it. They could have concocted lots of theories if it had become known."

"And now, at this lapse of time, the Press could not mention it for fear of libel. They'll think that the Doctor had done a moonlight flit, instead of paying his rent."

"It certainly looks like that," remarked Max with a laugh. "But I only wish we could induce Marion to tell us all she knows."

Charlie sighed.

"Yes," he said. "I only wish she would say something. But she refuses absolutely, and so we're left entirely in the dark."

"Well, all I can say is, that the Doctor would never wilfully leave me in ignorance of his whereabouts, especially at this moment. We have certain business matters together involving a probable gain of a good round sum. Therefore, it was surely to his interest to keep me in touch with him!" Max declared.

The man before him was silent.

Was it possible that he had misjudged him? Was he lying; or had he really gone to Cromwell Road in search of the Doctor and found the house untenanted and empty?

"It is a complete mystery," was all that Rolfe could say.

"Do you know, Charlie, a curious thought struck me the other day, and I mention it to you in all confidence. It may be absurd--but--well, somehow I can't get it out of my head."

"And what is it?" asked his friend with an eagerness just a little unusual.

Max paused. Should he speak? Or should he preserve silence? The mystery now held him bewildered. What had become of the dear old Doctor and the pretty girl with the tiny wisp of hair straying across her white brow? Yes. He would speak the vague impression that had, of late, been uppermost in his mind.

"Well," he said, "old Statham has financial interests in Servia, has he not?"

"Certainly. Quite a number. He floated their loan a few years ago."

"And has it not struck you then that he and the Doctor might be acquainted?"

"They were strangers," he exclaimed quickly, darting a strange look across at Barclay.

Max was somewhat surprised at the vehement and decisive nature of Charlie's declaration.

"And Maud never met the old fellow?"

"Never--to my knowledge."

"Statham has a number of friends and acquaintances whom you do not know.

The Doctor may have been one of them."

"Oh, Sam has very few secrets from me. I am his confidential secretary," was the other's rather cold response.

"I know--I know. But would it not be to Statham's interest to be on friendly terms with such a powerful factor in the Servian political world as Dr Petrovitch?"

"Well, it might. But you know how independent he is. He never goes into society, and has no personal friends. He's utterly alone in the world--the loneliest man in London."

"Then let us go a trifle further," said Max at last. "Answer me one question. Is it or is it not, a fact that you were at the house in Cromwell Road on the night of--of their disappearance?"

Rolfe's countenance changed in an instant. His lips went white.

"Why?" he faltered--"what do you mean to imply?--why--?"

"Because, Rolfe," the other said in a hard, determined voice, "because I saw you there--saw you with my own eyes!"

CHAPTER TWENTY FIVE.

TWO MEN AND A WOMAN.

The face of Charlie Rolfe went pale as death.