"The blood stain on its side," McIntyre answered.

"What--that!" Ferguson eyed McIntyre incredulously. "Come, sir, do you mean to tell me she noticed that little bit of a stain in a dark room?"

"She had an electric torch," shortly.

"But why should she turn the torch on this casket?" persisted the detective. "She came to the library for a book, and the bookcases are in another part of the room."

"Quite so, but the book she wished was lying on the top of this casket,"

replied McIntyre, meeting their level looks with one equally steadfast.

"I know because I left the book there."

Ferguson glanced from McIntyre to Kent and back again at the Colonel in non-plussed silence. The explanation was pat.

"I'd like to talk with Mrs. Brewster," he remarked dryly.

"Certainly." McIntyre pressed an electric b.u.t.ton. The summons was answered immediately by the new servant, Murray. "Ask Mrs. Brewster if she can see Detective Ferguson in the library, Murray," McIntyre directed.

"Beg pardon, sir, but Mrs. Brewster has just gone out," and with a bow Murray withdrew.

Kent, who had drawn forward a chair preparatory to sitting down and partic.i.p.ating in the interview with the widow, changed his mind.

"I must leave at once," he said, after consulting his watch. "Please inform Mrs. Brewster, Colonel, that I will be in my office this afternoon, and I expect her to make me the visit she postponed this morning. Ferguson," turning back to address the detective, "you'll find me at the Saratoga for the next hour. Good morning," and paying no attention to Colonel McIntyre's request to remain, he left the room.

There was no one in the hall and Kent debated a moment whether or not to ring for the servant and ask to see Barbara, but, at sight of the hall table, Grimes' confidences recurred to him and drove everything else out of his mind. Stopping before the table he contemplated its smooth surface before moving the few ornaments it held. Satisfied that no pillbox stood behind any of them, he pulled open the two drawers and tumbled their contents about. His efforts only brought to light some half-empty cigarette boxes, matches, a scratch pad or two, and old visiting cards.

Kent shut the drawers, picked up his hat, and took his cane from the tall china umbrella-stand by the hall table. As he stepped through the front doorway he caught sight of the end of his cane, which he was carrying tucked under his arm. Fastened to the ferule of the cane was the round top of a paste-board pill box.

Kent backed so swiftly into the house again that his figure blocked the closing of the front door, which he had started to pull shut after him.

Letting the door close gently he walked back to the umbrella stand. It was a tall heavy affair, and he had some difficulty in tipping it over and letting its contents spill on the floor. A soft exclamation escaped him as three little pellets rolled past him, and then came the bottom of a box.

With hasty fingers Kent picked them up, placed them in the box, and fitted on the top, first carefully smoothing over the hole made by his cane when thrust into the umbrella stand by the footman. Replacing the stand he wrapped the box containing the pills in his handkerchief and hurried from the house.

Kent found the operative from Detective Headquarters sitting on duty in Rochester's living room when he entered that apartment a quarter of an hour later.

"Any one called here?" he asked, as the man, whom he had met the night before, greeted him.

"Not a soul, Mr. Kent." Nelson suppressed a yawn; his relief was late in coming, and he had had little sleep the night before. "There's been no disturbance of any kind, not even a ring at the telephone."

Kent considered a moment, then sat down by the telephone and gave a number to Central.

"That you, Sylvester?" he called into the mouth-piece. "If Mrs. Brewster comes to the office, telephone me at Mr. Rochester's apartment, Franklin 52. Don't let Mrs. Brewster leave until I have seen her."

"Yes, sir," came the reply, and Kent hung up the receiver.

"Had any luncheon?" he asked Nelson as the man loitered around.

"Not yet"--Nelson's eyes brightened at the word. It was long past his usual meal hour.

"Run down to the cafe on the first floor and tell the head waiter to give you a square meal and charge it to me," Kent directed. "Order something substantial; you must be used up."

The man hung back. "Thank you, Mr. Kent, but I don't like to leave here until my relief comes," he objected.

"That's all right, I'll stay in the apartment until you return," and Kent settled the question by opening the door leading into the outer corridor. "Ferguson will be around shortly, so hurry."

Kent watched the man scurry toward the elevator shaft, then returned to Rochester's apartment and once more took up the telephone. The operative's reluctance to leave the apartment unguarded had altered his plans somewhat.

"Is this Dr. Stone's office?" he asked a moment later, as a faint "h.e.l.lo," came over the wire. "Oh, doctor, this is Kent. Please come over to Rochester's apartment; I would like to consult you in regard to an important matter. You'll come now? Thanks."

The doctor kept Kent waiting less than five minutes. The clock was striking one when he appeared, bland and smiling. Hardly waiting for him to select a seat Kent flung himself into a chair in front of Rochester's desk and laid the pill box on the writing pad.

"Now, doctor," he began, and his manner gained in seriousness, "what, in your opinion, killed Jimmie Turnbull?"

"The post-mortem examination proved that he had swallowed aconitine in sufficient quant.i.ty to cause death," Stone replied. "He undoubtedly died from the effects of that poison."

"Is aconitine difficult to procure?" asked Kent.

"It is often prescribed for fevers." Stone made himself comfortable in a near-by chair. "Aconitine is the alkaloid of aconite. I believe that in India it is frequently employed, not only for the destruction of wild beasts, but for criminal purposes. The India variety is known as the Bish poison."

Kent started--Bish poison--was he never to get away from the letter "B"?

"Can you procure Bish in this country?" he asked.

Stone considered the question. "You might be able to purchase it from some Hindoo residing or traveling in the United States," he said, after a pause. "I doubt if you could buy it in a drug store."

Kent heaved a sigh of relief as he hitched his chair closer to the physician.

"Did you prescribe a dose of aconitine for Mrs. Brewster recently?" he asked.

"I did, for an attack of rheumatic neuralgia." Stone eyed him curiously.

"What then, Kent?"

"Is this the box the medicine came in?" and Kent placed the cover in Stone's hand.

Stone turned the paste-board over and studied the defaced label. "I cannot answer that question positively," he said. "The label bears my name and that of the druggist, but the directions are missing."

"But the number's on it," put in Kent swiftly. "Come, Stone, call up the druggist, repeat the number to him, and ask if it calls for your aconitine prescription."

Stone hesitated as if about to speak, then, reaching out his hand, he picked up the telephone and held a short conversation with the drug clerk of the Thompson Pharmacy.

"That is the box which contained the aconitine pills for Mrs. Brewster,"

he said, when he had replaced the telephone. "Now, Kent, I have secured the information you wished; kindly tell me your reasons for desiring it."

It was Kent's turn to hesitate. "Do you know many instances where aconitine was used by murderers?" he questioned.

"N-no. I believe it was the drug used in the celebrated Lamson poison case," replied the physician slowly. "I cannot recall any others just at the moment."

"How about suicides?"