“A hell of a case this is! Not a lead—nothing to get your teeth in.”

He went to the archway and yanked the bell-cord viciously. When Sproot appeared he almost barked his demand that Mr. Rex Greene be produced at once; and he stood looking truculently after the retreating butler as if longing for an excuse to follow up his order with violence.

Rex came in nervously, a half-smoked cigarette hanging from his lips. His eyes were sunken; his cheeks sagged, and his short splay fingers fidgeted with the hem of his smoking-jacket, like those of a man under the influence of hyoscine. He gave us a resentful, half-frightened gaze, and planted himself aggressively before us, refusing to take the seat Markham indicated. Suddenly he demanded fiercely:

“Have you found out yet who killed Julia and Chester?”

“No,” Markham admitted; “but we’ve taken every precaution against any recurrence. . . .”

“Precaution? What have you done?”

“We’ve stationed a man both front and rear——”

A cackling laugh cut him short.

“A lot of good that’ll do! The person who’s after us Greenes has a key. He has a key, I tell you! And he can get in whenever he wants to, and nobody can stop him.”

“I think you exaggerate a little,” returned Markham mildly. “In any case, we hope to put our hands on him very soon. And that’s why I’ve asked you here again—it’s quite possible that you can help us.”