“Is that all?” Bitter disappointment rang in Charles’s voice.  “That might have been me.  I was out on the rocks that night, close to Flint House.”

“’Tweren’t you.”  Thalassa’s reply was so low as to be almost inaudible.  “I don’t know who it was, but I’ll take my Bible oath it weren’t you.”

“Who was it then?” Charles asked breathlessly.

“A dead man, or his spirit.  I know that now, though I laughed when he said it.  I know better now.”

He stopped suddenly, like one who has said too much, and looked moodily out to sea.

“What do you mean by that?”

“Never mind what I mean.  It’s nothing to do with you.  A man’s a fool when he gets talking.  The tongue trips you up.”

“Thalassa,” said Charles solemnly, “if you know anything which might throw the remotest light on this mystery it is your duty to reveal it.”

“It’s easy to talk.  But I swore—­I swore I would never tell.”

“This is the moment to forget your oath.”

“It’s fine to talk—­for you.  But he’d come back to haunt me, if he knew.”  He jerked his thumb in the direction of the distant churchyard where Robert Turold lay.

Charles looked at his grim and secret face in despair.  “I hope you realize what you are doing by keeping silence,” he said.

“I’m keeping a still tongue in my head, for one thing.”

“For one thing—­yes.  For another, you’re injuring Sisily—­you’re doing more than injure her.  You’re letting her remain under suspicion of her father’s death, in hiding in London, hunted by the police.  Yet she believed in you.  It was she who sent me to you, it was she who said:  ’Tell Thalassa from me to tell the truth, if he knows it.’  Is she mistaken in you, Thalassa?  Do you think more of your own skin than her safety?”

CHAPTER XXVIII

It was a strange story which Charles Turold heard by that grey Cornish sea—­a story touched with the glitter of adventurous fortune in the sombre setting of a trachytic island, where wine-dark breakers beat monotonously on a black beach of volcanic sand strewn with driftwood, kelp, dead shells, and the squirming forms of blindworms tossed up from the bowels of a dead sea.  It was there in the spell of solitude thirty years before that Robert Turold’s soul had yielded to temptation at the beck of his monstrous ambition.

That, however, was the end—­or what Robert Turold imagined to be the end—­of the story.  The listener was first invited to contemplate a scene in human progress when men gathered from the four corners of the earth and underwent incredible hardships of hunger, thirst, disease, lived like beasts and died like vermin for the sake of precious stones in the earth.  Thalassa brought up before the young man’s eyes a vivid picture of an African diamond rush of that period—­a corrugated iron settlement of one straggling street, knee-deep in sand, swarming