close watch on her father, the doctor left Mary, lighted his pipe, and strolled to the billiard-room.  Presently he patrolled the hall and pursued his own reflections.  Where his thoughts bent, there his body unconsciously turned, and, forgetting the injunction of the silent men aloft—­indeed, forgetting them also for a moment—­Mannering ascended the stairs and proceeded along the corridor toward the Grey Room.  But he did not get far.  Out of the darkness a figure rose and stopped him.  The man turned an electric torch on Dr. Mannering, and recognized him.  It appeared that while one detective kept guard outside, the others watched within.  At the sound of voices the door of the Grey Room opened, and in the bright light that streamed from it a weird figure stood—­a tall, black object with huge and flashing eyes and what looked like an elephant’s trunk descending from between them.  The watchers, wearing hoods and gas masks, resembled the fantastic demons of a Salvator Rosa, or Fuselli.  Their chief now accosted the doctor somewhat sharply.  He knew his name and received his apology, but bade him leave the corridor at once.  “I must, however, search you first,” said Frith.  “You were wrong to come,” he continued.  “This is no time to distract us.  Explain to-morrow, please.”

The doctor, after holding up his hands and submitting to a very close scrutiny, departed and swore at his own inadvertence.  He had forgotten that, in common with everybody else involved, he must bear the brunt of suspicion, and he perceived that his approach to the Grey Room, after it was clearly understood that none should on any account attempt to do so, must attract unpleasant attention to himself.  And he could offer no better excuse than that he had forgotten the order.  He apprehended an unpleasantness on the following day, and wondered at himself that he could have done anything so open to question.  Brain fag was a poor excuse, but he had none better.

In an hour he returned to Sir Walter, hoping to find him asleep; but the master of Chadlands was still reading, and in a frame of mind very quiet and peaceful.  He regretted the forgetfulness that had taken his friend into the forbidden gallery.

“I am concerned for Mary,” he said.  “She is only keeping up at a terrible cost of nervous power.  It is more than time that she was away; but she will not go until I am able to accompany her.”

“It should not be long.  We must hope they will get to the bottom of it soon, if not to-night.  I am most anxious for both of you to be off.”

“We design to go to Italy.  She shrinks from the Riviera and longs for Florence, or some such peaceful place.”

“It will be cold there.”

“Cold won’t hurt us.”

“Shall you shut up Chadlands?”

“Impossible.  It is the only home of half my elder people.  But, if nothing is discovered and we are still left without an explanation, I shall seal the Grey Room—­windows, door, and hearth—­ unless the authorities direct otherwise.  I wish I could fill the place with solid stone or concrete, so that it would cease to be a room at all.”