Kennedy paused, then finished with irresistibly dramatic logic;

“Who else but the man who held the secret of Minna Pitts’s past and power over her future so long as he could keep alive the unfortunate Thornton—­the up-to-date doctor who substituted an elixir of death at night for the elixir of life prescribed for you by him in the daytime—­Dr. Lord.”

Kennedy had moved quietly toward the door.  It was unnecessary.  Dr. Lord was cornered and knew it.  He made no fight.  In fact, instantly his keen mind was busy outlining his battle in court, relying on the conflicting testimony of hired experts.

“Minna,” murmured Pitts, falling back, exhausted by the excitement, on his pillows, “Minna—­forgive?  What is there to forgive?  The only thing to do is to correct.  I shall be well—­soon now—­my dear.  Then all will be straightened out.”

“Walter,” whispered Kennedy to me, “while we are waiting, you can arrange to have Thornton cared for at Dr. Hodge’s Sanitarium.”

He handed me a card with the directions where to take the unfortunate man.  When at last I had Thornton placed where no one else could do any harm through him, I hastened back to the laboratory.

Craig was still there, waiting alone.

“That Dr. Lord will be a tough customer,” he remarked.  “Of course you’re not interested in what happens in a case after we have caught the criminal.  But that often is really only the beginning of the fight.  We’ve got him safely lodged in the Tombs now, however.”

“I wish there was some elixir for fatigue,” I remarked, as we closed the laboratory that night.

“There is,” he replied.  “A homeopathic remedy—­more fatigue.”

We started on our usual brisk roundabout walk to the apartment.  But instead of going to bed, Kennedy drew a book from the bookcase.

“I shall read myself to sleep to-night,” he explained, settling deeply in his chair.

As for me, I went directly to my room, planning that to-morrow I would take several hours off and catch up in my notes.

That morning Kennedy was summoned downtown and had to interrupt more important duties in order to appear before Dr. Leslie in the coroner’s inquest over the death of the chef.  Dr. Lord was held for the Grand Jury, but it was not until nearly noon that Craig returned.

We were just about to go out to luncheon, when the door buzzer sounded.

“A note for Mr. Kennedy,” announced a man in a police uniform, with a blue anchor edged with white on his coat sleeve.

Craig tore open the envelope quickly with his forefinger.  Headed “Harbour Police, Station No. 3, Staten Island,” was an urgent message from our old friend Deputy Commissioner O’Connor.

“I have taken personal charge of a case here that is sufficiently out of the ordinary to interest you,” I read when Kennedy tossed the note over to me and nodded to the man from the harbour squad to wait for us.  “The Curtis family wish to retain a private detective to work in conjunction with the police in investigating the death of Bertha Curtis, whose body was found this morning in the waters of Kill van Kull.”