as kent walked into the library he found colonel mcintyre by his side; the latter's even breathing gave no indication of the haste he had made down the staircase to catch up with kent.

detective ferguson hardly noted their arrival, his attention being given wholly to the examination of the venetian casket which had played such an important part in the drama of the night before. the casket and its companion piece stood on either side of the room near a window recess. the long straight shape of the high boxes on their graceful base gave no indication of the use to which they had been put in ancient days, but made attractive as well as unique pieces of furniture.

kent crossed the library and, after looking inside the casket, examined the exterior with care.

“don't touch that crest,” cautioned ferguson, observing that kent's glance remained focused on the blood-stained, raised letter “b” and the carving back of it. “in fact, don't touch any part of the casket, i'm trying to get finger prints.”

kent barely heard the warning as he turned to mcintyre.

“haven't i seen that letter 'b' design on your stationery, colonel?” he asked.

“barbara uses it,” was the reply. “she fancied the antique lettering, and copied the 'b' for the engraver; she is handy with her pen, you know.”

“did she wish the 'b' for a seal?” inquired kent.

“yes, she had a seal made like it also.” mcintyre moved closer to the casket. “found anything, ferguson?”

the detective withdrew his head from the opening at the end of the casket, and regarded the furniture vexedly.

“not a thing,” he acknowledged. “except i am convinced that it required dexterity to slip grimes inside the casket. the butler is small and slight, but he must have been unconscious from that tap on the forehead and, therefore, a dead weight. whoever picked him up must have been some athlete, and”—running his eyes up and down colonel mcintyre's well-knit, erect frame—“pretty familiar with the workings of this casket.”

“pooh! it's not so difficult a feat,” mcintyre shrugged his shoulders disdainfully. “my daughters, as children, used to play hide and seek inside the casket with each new governess.”

ferguson stepped forward briskly. “mr. kent, let me see if i can lift you inside the casket; make yourself limp—that's it!” as kent, entering into the investigation heart and soul, relaxed his muscles and fell back against the detective.

a moment later he was swung upward and pushed head-first inside the casket and the door closed. the air, though close, was not unpleasant and kent, his eyes growing gradually accustomed to the dark interior, tried to discover the trap door at the top of the box but without success. putting out his hands he felt along the top. the height of the casket did not permit him to sit up, so he was obliged to slide his body down toward his feet to feel along the sides of the casket. this maneuver soon brought his knees in violent contact with the top, and at the sound ferguson opened the door and assisted him out.

“had enough of it?” he asked, viewing kent's reddened cheeks with faint amusement. “i wonder if grimes could breathe in there for any lengthy period. if so, it would help establish the time which elapsed between his being incarcerated and your finding him, colonel.”

“how so?” demanded mcintyre.

“well, if he couldn't get air and you hadn't discovered him at once, he'd have died,” explained ferguson. “if you did find him immediately the person who knocked him down must have made a lightning escape.”

“air does get in the casket in some way,” broke in kent. “it wasn't so bad inside. colonel mcintyre,” kent stopped a moment to remove a piece of red sealing wax clinging to the cuff of his suit. it had not been there when he entered the casket. kent dropped the wax in his vest pocket as he again addressed his host. “who first discovered grimes in the casket?”

“mrs. brewster.”

“and what was mrs. brewster doing in the library at that hour?” glancing keenly at mcintyre as he put the question.

“she could not sleep and came down for a book,” explained the colonel.

ferguson, who had walked several times around the library, looking behind first one and then the other of the seven doors, paused to ask:

“what attracted mrs. brewster's attention to the casket?”

“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 button. 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 participating 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 “hello,” 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 quantity 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?”

“it is seldom, if ever, used for suicides.” stone spoke with more assurance. “i have found in my practice, kent, that suicides can be classed as follows: drowning by the young, pistols by the adult, and hanging by the aged; women generally prefer asphyxiation, using illuminating gas. but this is beside the question, unless”—bending a penetrating look at his companion—“unless you believe jimmie turnbull committed suicide.”

“that idea has occurred to me,” admitted kent. “but it doesn't square with other facts which have developed, nor is it in keeping with the character of the man.”

“men who suffer from a mortal disease sometimes commit desperate acts, not at all in accord with their previous conduct,” responded stone gravely. “come, kent, you have not answered my question. why did you wish information about this box of aconitine pills prescribed for mrs. brewster during her attack of neuralgia?”

“you have just stated that aconitine is not usually administered to murder a person,” kent spoke seriously, choosing his words with care. “do you wonder then, that i consider it more than a coincidence that jimmie turnbull should have died from a dose of that poison, and that the drug should have been prescribed for one of the inmates of the house he visited shortly before his death?”

the physician sat upright, his face had grown gray. “mr. kent,” he commenced indignantly, “are you aware what you are insinuating? are you, also, aware that mrs. brewster is my cousin, a charming, honorable woman, without a stain on her character?”

kent set the bottom of the box containing the pills in front of the doctor.

“i have found out that this box, with its dangerous drug, was left on the hall table in the mcintyre house; apparently any one had access to its contents, therefore my remarks are not directed against mrs. brewster any more than against any person in the mcintyre household, from the colonel to the servants. i found these three pills at the mcintyre house this morning; how many did your prescription call for?”

stone picked up the small pills and, as he balanced them in his palm, his manner grew more alert. suddenly he dropped two back in the box and touched the third pill with the tip of his tongue; not content with that he crushed it in his fingers, sniffed the drug, and again tested it with his tongue. his expression was peculiar as he looked up at kent.

“these are not aconitine pills,” he stated positively. “they are nitro-glycerine. how did they get in this box?”

kent rubbed his chin in bewilderment. the box bearing the aconitine label and the pills had all rolled out of the china umbrella stand, and he had taken it for granted that the pills belonged in the box.

“i found them loose in the same receptacle,” he explained. “and concluded they were what remained of the aconitine pills which grimes, the mcintyre butler, said he left on the hall table sunday afternoon.”

stone smiled with what kent, who was watching him closely, judged to be an odd mixture of relief and apprehension.

“you could not have found more dissimilar medicine to go in this pill box, although the two kinds of pills are identical in color and size,” he said. “aconitine depresses the heart action while the other stimulates it.”

the physician's statement fell on deaf ears. raising his head after contemplating the pills, kent had looked across the room and his glance had fallen on a wing chair, standing just inside the doorway of the living room, and thrown partly in shadow by the portieres. the wing of the chair appeared to move. kent rubbed his eyes and looking again, caught the same slight movement.

bounding toward the chair kent saw that the brown shape which he had mistaken for part of the tufted upholstery was the sleek brown hair of a man's well-shaped head. he halted abruptly on meeting the gaze of a pair of mocking eyes.

“rochester?” he gasped unbelievingly. “rochester!”

his partner laughed softly as stone approached. “i have been an interested listener,” he said. “let me complete the good doctor's argument. nitro-glycerine would have benefitted jimmie turnbull and his feeble heart; whereas the missing aconitine pills killed him.”

stone regarded him with severity. “how did you get in this apartment?” he demanded, declining the challenge rochester had offered in addressing his opinion of turnbull's death directly to him.

rochester dangled his bunch of keys in the physician's face and smiled at his excited partner. “if you two hadn't been so absorbed in your conversation you would have heard me walk in,” he remarked.

“where have you been?” demanded kent, partly recovering from his astonishment which had deprived him of speech.

“i decided to take a vacation at a moment's notice.” rochester spoke with the same slow drawl which was characteristic of him. “you should be accustomed to my eccentricities by this time, harry.”

“we are,” announced detective ferguson from the hallway, where he and nelson had been silent witnesses of the scene. “and we'll give you a chance to explain them in the police court.”

“on what charge?” demanded rochester.

“poisoning your room-mate, mr. turnbull,” replied the detective, drawing out a pair of handcuffs. “you are mighty clever, mr. rochester. i've got to hand it to you for your mysterious disappearances in and out of this apartment, and for murdering mr. turnbull right in the police court in the presence of the judge, police officials, and spectators.”

kent stepped forward at sight of the handcuffs and laid a restraining hand on the detective's shoulder. rochester saw the movement, guessed kent's intention, and smiled.

“we can settle the case here,” he said cheerfully. “no need of troubling the police judge. now, mr. detective, how did i kill jimmie turnbull before all those people without any one becoming aware of the fact?”

“slipped the poison in the glass of water you handed him,” answered ferguson promptly. “a nervy sleight-of-hand, but you'll swing for it.”

rochester's smile was exasperating as he turned to dr. stone.

“judging from stone's remarks about aconitine—which i overheard,” he interpolated. “i gather the doctor is tolerably familiar with the action of the drug. does aconitine kill instantly, doctor?”

stone cleared his throat before speaking. “no; the fatal period averages about four hours,” he said, and rochester's eyes sparkled as he looked up at the detective.

“jimmie died almost immediately after i handed him that drink of water,” he declared. “if you wish to know who administered that aconitine poison, you will have to find out who jimmie was with at the mcintyre house in the early hours of tuesday morning.”

the sharp imperative ring of the telephone bell cut the silence which followed. kent, standing nearest the instrument, picked it up, and recognized sylvester's voice over the wire.

“a message has just come, mr. kent,” he called, “from mrs. brewster saying that she will be in your office at four o'clock.”