But Chayne could finish it for himself.  There could be no advantage to any one if Walter Hine died.  But then why the cocaine?  Why the incident of the lighted window?

“Yes,” he said, in perplexity, “I can corroborate that.  It happened that my friend John Lattery, who was killed in Switzerland, was also connected with Joseph Hine.  He also would have inherited; and I knew from him that the old man did not recognize his heirs.  But—­but Walter Hine had money—­some money, at all events.  And he earned none.  From whom did he get it?”

Sylvia shook her head.

“I do not know.”

“Had he no other relations, no friends?”

“None who would have made him an allowance.”

Chayne pondered over that question.  For in the answer to it he was convinced he would find the explanation of the mystery.  If money was given to Walter Hine, who had apparently no rich relations but his grandfather, and certainly no rich friends, it would have been given with some object.  To discover the giver and his object—­that was the problem.

“Think!  Did he never speak of any one?”

Sylvia searched her memories.

“No,” she said.  “He never spoke of his private affairs.  He always led us to understand that he drew an allowance from his grandfather.”

“But your father found that that was untrue when you were in Dorsetshire, ten months ago.  For the card-playing and the bets ceased.”

“Yes,” Sylvia agreed thoughtfully.  Then her face brightened.  “I remember a morning when Mr. Hine was in trouble.  Wait a moment!  He had a letter.  We were at breakfast and the letter came from Captain Barstow.  There was some phrase in the letter which Mr. Hine repeated.  ’As between gentlemen’—­that was it!  I remember thinking at the time what in the world Captain Barstow could know about gentlemen; and wondering why the phrase should trouble Mr. Hine.  And that morning Mr. Hine went to London.”

“Oh, did he?” cried Chayne. “‘As between gentlemen.’  Had Hine been losing money lately to Captain Barstow?”

“Yes, on the day when you first came.”

“The starlings,” exclaimed Chayne in some excitement.  “That’s it—­Walter Hine owes money to Captain Barstow which he can’t pay.  Barstow writes for it—­a debt of honor between gentlemen—­one can imagine the letter.  Hine goes up to London.  Well, what then?”

Sylvia started.

“My father went to London two days afterward.”

“Are you sure?”

It seemed to Chayne that they were getting hot in their search.

“Quite sure.  For I remember that after his return his manner changed.  What I thought to be the new plot was begun.  The cards disappeared, the bets ceased, Mr. Parminter was brought down with the cocaine.  I remember it all clearly.  For I always associated the change with my father’s journey to London.  You came one evening—­do you remember?  You found me alone and afraid.  My father and Walter Hine were walking arm-in-arm in the garden.  That was afterward.”