It was a neat and well-appointed room entirely lined with a medical library.  At the other end of it was a ponderous and polished desk with an incandescent lamp on it, the light of which was just sufficient to show a slender, well-bred figure in an ordinary medical black frock-coat, whose head, quite silvered with age, was bent over neat piles of notes.  This gentleman looked up for an instant as they entered, and the lamplight fell on his glittering spectacles and long, clean-shaven face—­a face which would have been simply like an aristocrat’s but that a certain lion poise of the head and long cleft in the chin made it look more like a very handsome actor’s.  It was only for a flash that his face was thus lifted.  Then he bent his silver head over his notes once more, and said, without looking up again: 

“I told you, Dr. Quayle, that these men were to go to cells B and C.”

Turnbull and MacIan looked at each other, and said more than they could ever say with tongues or swords.  Among other things they said that to that particular Head of the institution it was a waste of time to appeal, and they followed Dr. Quayle out of the room.

The instant they stepped out into the corridor four sturdy figures stepped from four sides, pinioned them, and ran them along the galleries.  They might very likely have thrown their captors right and left had they been inclined to resist, but for some nameless reason they were more inclined to laugh.  A mixture of mad irony with childish curiosity made them feel quite inclined to see what next twist would be taken by their imbecile luck.  They were dragged down countless cold avenues lined with glazed tiles, different only in being of different lengths and set at different angles.  They were so many and so monotonous that to escape back by them would have been far harder than fleeing from the Hampton Court maze.  Only the fact that windows grew fewer, coming at longer intervals, and the fact that when the windows did come they seemed shadowed and let in less light, showed that they were winding into the core or belly of some enormous building.  After a little time the glazed corridors began to be lit by electricity.

At last, when they had walked nearly a mile in those white and polished tunnels, they came with quite a shock to the futile finality of a cul-de-sac.  All that white and weary journey ended suddenly in an oblong space and a blank white wall.  But in the white wall there were two iron doors painted white on which were written, respectively, in neat black capitals B and C.

“You go in here, sir,” said the leader of the officials, quite respectfully, “and you in here.”

But before the doors had clanged upon their dazed victims, MacIan had been able to say to Turnbull with a strange drawl of significance:  “I wonder who A is.”

Turnbull made an automatic struggle before he allowed himself to be thrown into the cell.  Hence it happened that he was the last to enter, and was still full of the exhilaration of the adventures for at least five minutes after the echo of the clanging door had died away.