“Poor Diane!” he muttered.  “She has paid a frightful penalty for the sins of her wayward life—­more than she deserved.  She must have been lying dead when I rapped on her door last night.  Yes, and the fatal blow had been struck but a short time before!  The assassin was the foreign-looking man who came down the stairs as I went up!  There can be no doubt of it!  But who was he?  And what was his motive?  A discarded lover, perhaps!  What else could have prompted the deed?”

He suddenly paused, and reeled against the wall; he clenched his hands, and a look of sharp horror distorted his face.

“By heavens, this is awful!” he gasped.  “I never thought of it before!  The police are looking for me—­I remember now that I met the landlady when I left the house.  I brushed against her and apologized, and she stared straight at me!  And the real murderer—­the foreigner—­appears to have been seen by nobody except myself.  What shall I do?  It is on me that suspicion has fallen!”

The realization of his danger unnerved and stupefied Jack for an instant.  Dread phantoms of arrest and imprisonment, of trial and sentence, rose before his eyes.  One moment he determined to flee the country; the next he resolved to surrender to the police and tell all that he knew, so that the real murderer might be sought for without loss of time.  But the latter course was risky, fraught with terrible possibilities.  The evidence would be strong against him.  He remembered Diane’s letter.  He must destroy it!  He hurriedly searched the pockets of the clothing he had worn on the previous night, but in vain.

“The letter is gone—­I have lost it!” he concluded, with a sinking heart.  “But where and how?  And if it is found—­”

There was a sharp rap at the door, and as quickly it opened, without invitation.  Two stern-looking men, dressed in plain clothes, stepped into the room.  Jack knew at once what the visit meant, and with a supreme effort he braced himself to meet the ordeal.  It was hard work to stand erect and to keep his face from twitching.

“You are John Vernon?” demanded one of the men.

“Yes.”

“I will be very brief, sir.  I am a Scotland Yard officer, and I am here to arrest you on suspicion of having murdered your wife, known as Diane Merode, at Number 324 Beak street, last night.”

“I expected this,” Jack replied.  “I have just seen the paper—­I knew nothing of the crime before.  I am entirely innocent, though I admit that the circumstances—­”

“I warn you not to say anything that may incriminate yourself.  You must come with me, sir!”

“I understand that, and I will go quietly.  I am quite ready.  And at the proper time I will speak.”

There was no delay.  One of the officers remained to search the apartments, and Jack accompanied the other downstairs.  They got into a cab and drove off, while Mrs. Jones shook her fist at them from the doorway, loudly protesting that she was a disgraced and ruined woman forever.