As we got out, the detective laid his hand on Guy’s arm.  “Gently, sir,” he said.  “You must be careful.  We’ve not quite so much proof as I could wish.  It would be straining a point to arrest him as it stands.  I’d do it though—­for you.  Get him to talk, and don’t hurry him; he’s safe to commit himself; and we’ll nail him at the first word.  My comrade says he has not left his bed since yesterday.  Perhaps he’s ill.  All the better.  We can frighten him if we get his man out of the way.”

Guy’s hand was on the bell before the last words were said, and he rang it sharply.  The two officers drew back into the shadow.

In a few moments an old man opened the door, whom we guessed to be Bruce’s attendant.  He had one of those stubborn, rough-hewn faces that even white hair can not soften any more than hoar-frost can the outline of a granite crag.

“What’s ye’re wull?” he drawled out, in the rugged Aberdeen Doric.

“I wish to see Mr. Bruce.”

“No sic a pairson here,” was the reply, accompanied by a vigorous effort to close the door.

A heavy groan, proceeding from a room on the ground floor, gave him the lie as he spoke.  Guy threw up his head like a hound breaking from scent to view, and thrust Macbane back violently.  The old man staggered and fell; but he clung round Livingstone’s knees, as he groveled, till he was actually trampled down.  There was a difficulty in the lock somewhere; but bolt and staple were torn away in an instant by the furious hand that grasped the handle, and so at last we stood in the presence of the man we had sought so long.

Do you remember that hideous picture in Hogarth’s “Two Apprentices,” where the sleeping robber is alarmed by the crash in the chimney?  That was exactly Bruce’s attitude.  He had started into a sitting posture, and was braced up on his hands, his face thrust forward, half covered by the straight unkempt hair.  What a face it was!  White and flecked with sweat-drops, marbled here and there with livid stains, the lips quivering and working till they twisted themselves sometimes into a ghastly mockery of a smile, the long teeth gleaming more wolfish than ever.  The iris of the prominent eyes had grown yellowish, and the whites were bloodshot, so that the light seemed to flash from them tawnily.

Bruce had always been very much afraid of Livingstone.  His terror had gone on increasing during months of relentless pursuit; it had reached its climax now.  Guy stood at the foot of the bed, contemplating the unhappy wretch with a cruel calmness that seemed to drive him wild.  He writhed and cowered under the fixed gaze, as if it gave him physical pain.

“What are you here for?” he screamed out at last.

In strong contrast to the shrill, strained voice, the answer came slow and stern.  “To arrest Charles Forrester’s murderer.”