“Stop him!” he cried.  “Take him away!  It’s Craig—­his spirit!  He came to me in the garage, he followed me through the grounds, he mocked at me when I hid in the tree.  He’s there now, kneeling before the fireplace.  Why can’t I kill him!  He is coming!  Stop him, some one!”

No one spoke or moved; no one, indeed, had the power.  Then at last Quest found words.

“There is no one in the room, Professor,” he said, “except us.”

The sound of a human voice seemed to produce a strange effect.  The Professor straightened himself, shook his head, his hands dropped to his side.  He turned around and faced them.  He was ghastly pale, but his smile was once more the smile of the amiable naturalist.

“My friends,” he said, “forgive me.  I am very old, and the events of these last few hours have unnerved me.  Forgive me.”

He groped for a moment and sank into a chair.  Quest fetched a decanter and a glass from the sideboard, poured out some wine and held it to his lips.  The Professor drank it eagerly.

“My dear friend,” he exclaimed, “you have saved me!  I have something to tell you, something I must tell you at once, but not here.  I loathe this place.  Let me come with you to your rooms.”

“As you please,” Quest answered calmly.

The Professor rose hastily to his feet.  As he turned around, he saw French concealing something in his hands.  He shivered.

“I don’t need those!” he cried.  “What are they?  Handcuffs?  Ah, no!  I am only too anxious to tell you all that I know.  Take care of me, Mr. Quest.  Take me with you.”

He gripped Quest’s arm.  In silence they passed from the room, in silence they took their places once more in the automobiles, in silence they drove without a pause to Quest’s rooms.  The Professor seemed to breathe more freely as they left the neighbourhood of his house behind.  He walked up the stairs to Quest’s library almost blithely.  If he was aware of it, he took no notice of French and the two plain-clothes men behind.  As he stepped into the room, he drew a long sigh of relief.  He made his way at once to his favourite easy-chair, threw off his overcoat and leaned back.

“Quest,” he pronounced, “you are the best friend I have in my life!  It is you who have rid me of my great burden.  Tell me—­help me a little with my story—­have you read that page from the Medical Journal which Craig has kept locked up all these years?”

“We have all read it,” Quest replied.

“It was forged,” the Professor declared firmly, “forged by Craig.  All the years since, he has blackmailed me.  I have been his servant and his tool.  I have been afraid to speak.  At last I am free of him.  Thank God!”

“Craig, after all,” French muttered.

The Professor sat with a faint, wistful smile upon the corners of his lips, looking around at all of them.  His face had become like the face of a child, eager for sympathy and kindness.