Sir Chichester broke the silence.

“But we left Stella here when we went to Harrel,” he began, and Hillyard interrupted him.

“There’s no doubt that Stella sent the message,” he said.  “Your car, Mrs. Brown’s and Luttrell’s, were all used to take us to Harrel.  One car remained in your garage—­Stella’s.”

“But there wouldn’t be time for that car to reach London.”  Sir Chichester fought against Hillyard’s statement.  He did not want to believe it.  He did not want to think of it.  It brought him within too near a view of that horrid brink where overtried nature grows dizzy and whirls down into blackness.

“Just time,” Hillyard answered relentlessly, “if you will follow me.  Joan certainly returned here last night—­that I know, as you know.  But she was back again in the ball-room at Harrel within a few minutes of ten o’clock.  She must have left Mrs. Croyle a quarter before ten—­that, at the latest.”

“Yes,” Millie Splay agreed.

“Well, I have myself crossed Putney Bridge after leaving here, within ten minutes under the two hours.  And that in the daytime.  Stella had time enough for her purpose.  It was night and little traffic on the road.  She writes her letter, sends Jenny with it to the garage, and the car reaches the Harpoon office by twelve.”

“But its return?” asked Sir Chichester.

“Simpler still.  Your gates were left open last night, and we returned from Harrel at four in the morning.  Stella’s chauffeur hands in his letter, comes back by the way he went and is home here at Rackham an hour and a half before we thought of saying good-bye to Mrs. Willoughby.  That is the way it happened.  That is the way it must have happened,” Hillyard concluded energetically.  “For it’s the only way it could have happened.”

Luttrell, though he had been a listener and nothing else throughout Martin’s statement, had cherished a hope that somehow it might be discovered that Stella had died by an accident.  That she should die by her own hand, in this house, under the same roof as Joan, and because of one year which had ended at Stockholm—­oh, to him a generation back!—­was an idea of irrepressible horror.  He could not shake off some sense of guiltiness.  He had argued with it all that day, discovering the most excellent contentions, but at the end, not one of them had succeeded in weakening in the least degree his inward conviction that he had his share in Stella’s death.  Unless her death was an accident, unless, using her drug, she fell asleep and so drifted unintentionally out of life!  He still caught at that hope.

“Are you sure that the handwriting was Stella’s?” he asked.

“Quite.  I saw the letter.”

“Did the editor give it to you?”

“No, he had to keep it for his own protection.”

“That’s a pity,” said Harry.  A pity—­or a relief, since, without that evidence before his eyes, he could still insist upon his pretence.