Barbara McIntyre made the round of the library for the fifth time, testing each of the seven doors opening into it to see that they were closed behind their portieres, then she turned back to her sister, who sat cross-logged before a small safe.

“Any luck?” she asked

Instead of replying Helen removed the key from the lock of the steel door and regarded it attentively. The safe was of an obsolete pattern and in place of the customary combination lock, was opened by means of a key, unique in appearance.

“It is certainly the key which father mislaid six months ago,” she declared. “Grimes found it just after father had a new key made and gave it to me. And yet I can't get the door open.”

“Let me try.” Barbara crouched down by her sister and inserted the key again in the lock, but her efforts met with no results, and after five minutes' steady manipulation she gave up the attempt. “I am afraid it is impossible,” she admitted. “Seems to me I have heard that the lost key will not open a safe after a new key has been supplied.”

Helen rose slowly to her feet, stretching her cramped limbs carefully as she did so, and sank down in the nearest chair. Her attitude indicated dejection.

“Then we can't find the envelope,” she muttered. “Hurry, Babs, and close the outer door; father may return at any moment.”

Barbara obeyed the injunction with such alacrity that the door, concealing the space in the wall where stood the safe, flew to with a bang and the twins jumped nervously.

“Take care!” exclaimed Helen sharply. “Do you wish to arouse the household?”

“No danger of that.” But Barbara glanced apprehensively about the library in spite of her reassuring statement. “The servants are either out or upstairs, and Margaret Brewster is writing letters in our sitting room.”

“Hadn't you better go upstairs and join her?” Helen suggested. “Do, Babs,” as her sister hesitated. “I cannot feel sure that she will not interrupt us.”

“But my joining her won't keep Margaret upstairs,” objected Barbara.

“No, but you can call and warn me if she is on her way down, and that will give me time to—to straighten father's papers,” going over to a large carved table littered with magazines, letters, and silver ornaments. Her sister did not move, and she glanced at her with an irritated air, very foreign to her customary manner. “Go, Barbara.”

The curt command brought a stare from Barbara, but it did not accelerate her halting footsteps; instead she moved with even greater slowness toward the hall door; her active brain tormented with an unspoken and unanswered question. Why was Helen so anxious for her departure? She had accepted her offer of assistance in her search of the library with such marked reluctance that Barbara had marveled at the time, and now...

“Are you quite sure, Helen, that father had the envelope in his pocket this morning?” she asked for the third time since the search began.

“He had an envelope—I caught a glimpse of the red seal,” answered Helen. “Then, just before dinner he was putting some papers in the safe. Oh, if Grimes had only come in a moment sooner to announce dinner, I might have had a chance to look in the safe before father closed the door.”

Whatever reply Barbara intended making was checked by the rattling of the knob of the hall door; it turned slowly, the door opened and, pushing aside the portieres drawn across the entrance, Margaret Brewster glided in. “So glad to find you,” she cooed. “But why have you closed up the room and turned on all the lights?”

“To see better,” retorted Barbara promptly as the widow's eyes roved around the large room, taking silent note of the drawn curtains and portieres, and the somewhat disarranged furniture. “Come inside, Margaret, and help us in our search.”

“For what?” The widow tried to keep her tone natural, but a certain shrill alertness crept into it and Barbara, who was watching her closely, was quick to detect the change. Helen's color altered at the question, and she observed the widow's entrance with veiled hostility.

“For my seal,” Barbara answered. “The one with the big letter 'B.' Have you seen it?”

“I?—No.” The widow took a chair uninvited near Helen. “You look tired, Helen dear; why don't you go to bed?”

“I could not sleep if I did.” Helen passed a nervous finger across her eyes. “But don't let me keep you and Babs up; it won't take me long to arrange to-morrow's market order for Grimes.”

Under pretense of searching for pencil and paper Helen contrived to see the address of every letter lying on the table, but the envelope she sought, with its red seal, was not among them. When she looked up again, pencil and paper in hand, she found Mrs. Brewster leaning lazily back and regarding her from under half-closed lids. “You are very like your father, Helen,” she commented softly.

The girl stiffened. “Am I? Babs and I are generally thought to resemble our mother.”

“In appearance, yes; but I mean mannerisms—for instance, the way of holding your pencil, your handwriting, even, closely resembles your father's.” Mrs. Brewster pointed to the notes Helen was scribbling on the paper and to an open letter bearing Colonel McIntyre's signature at the bottom of the sheet lying beside the pad to illustrate her meaning. “These are almost identical.”

“You are a close observer.” Helen completed her memorandum and laid it aside. “What became of father?”

“He went to a stag supper at the Willard,” chimed in Barbara, stopping her aimless walk about the library. “He said we were not to wait up for him.”

Helen pushed back her chair and rose with some abruptness.

“I am more tired than I realized,” she remarked and involuntarily stretched her weary muscles. “Come, Margaret,” laying a persuasive hand on the widow's shoulder. “Be a trump and rub my forehead with cologne as you used to do abroad when I had a headache. It always put me to sleep then; and, oh, how I long for sleep now!”

There was infinite pathos in her voice and Mrs. Brewster sprang up and threw her arm about her in ready sympathy.

“You poor darling!” she exclaimed. “Let me put you to bed; Mammy taught me the art of soothing frayed nerves. Come with us, Babs,” holding out her left hand to Barbara. But the latter, with a dexterous twist, slipped away from her touch.

“I must stay and straighten the library,” she announced.

Mrs. Brewster's delicate color had deepened. “It would be as well to open some of the doors,” she agreed coldly. “The library looks odd, not to say funereal,” she glanced down the spacious room and shivered ever so slightly. “Do, Babs, put out some of the lights; they are blinding.”

“Oh, I'll turn them all out”—Barbara sought the electric switch.

“But your father—”

“No need to worry about father; he can find his way about in the dark like a cat,” responded Barbara with unabated cheerfulness. “Seems to me, Margaret, you and father are getting mighty chummy these days.”

The sudden darkness into which Barbara's impatient fingers, pressing against the electric light buttons, plunged the library and its occupants, prevented her seeing the curious glance which Mrs. Brewster shot at her. Helen, who had listened to their chatter with growing impatience, looked back over her shoulder.

“Hurry, Barbara, and come upstairs. Now, Margaret,” and she piloted the widow along the hall toward the staircase without giving her an opportunity to answer Barbara's last remark. Barbara, pausing only long enough to pull back the portieres of the hall door and arrange them as they hung customarily, turned to go upstairs just as Grimes came down the hall from the dining room carrying a large tray with pitchers of ice water and glasses.

“I thought you had gone to your room, Grimes,” she remarked, as the butler waited respectfully for her to pass him.

“I've just come in, miss, and found Murray had left the tray in the dining room,” explained Grimes hurriedly. “I hope, miss, I'll not disturb the ladies by knocking at their doors now with this ice water.”

“Oh, no, Mrs. Brewster and Miss Helen have only just gone upstairs.” Barbara paused in front of the butler and poured out a glass of water. “I can't wait, Grimes, I am too thirsty.”

“Certainly, miss, that's all right.” Grimes craned his head around and looked up and down the hall, then leaning over he placed the tray on a convenient table and stepped close to Barbara.

“I've been reading the newspapers very carefully, miss,” he began, taking care to keep his voice lowered. “Especially that part of Mr. Turnbull's inquest which tells about the post-mortem.”

“Well, what then?” asked Barbara quickly as the butler paused and again glanced up and down the hall.

“Just this, miss,” he spoke almost in a whisper. “The doctors do say poor Mr. Turnbull was poisoned by acca—aconitine,” stumbling over the word. “It's a curious thing, miss, that I brought some of that very drug into this house last Sunday.”

“You did!” Barbara's fresh young voice rose in astonishment.

“Hush, miss!” The butler raised both hands. “Hush!” He glanced cautiously around, then continued. “Colonel McIntyre sent me to the druggist with a prescription from Dr. Stone for Mrs. Brewster when she had romantic neuralgia.”

“Had what?” Barbara looked puzzled, then giggled, but her mirth quickly altered to seriousness at sight of the butler's expression. “Mrs. Brewster had a touch of rheumatic neuralgia the first of the month; do you refer to that?”

“Yes, miss.” Grimes spoke more rapidly, but kept his voice lowered. “The druggist told me what the pills were when I exclaimed at their size—regular little pellets, no bigger than that,” he demonstrated the size with the tip of his little finger, and would have added more but the gong over the front door rang out with such suddenness that both he and Barbara started violently.

“Just a moment, miss,” and he hurried to the front bell, to return after a brief colloquy with a messenger boy, bearing a letter. “It's for Mrs. Brewster, miss,” he explained, as Barbara held out her hand.

“I'll give it to her and this also,” Barbara took the envelope and a small ice pitcher and glass. “Good night, Grimes. Oh,” she stopped midway up the staircase and waited for the butler to overtake her, “Grimes, to whom did you give the aconitine on Sunday?”

“I didn't give it to nobody, miss.” The butler was a trifle short of breath; his years did not permit him to keep pace with the twins. “I was in a great hurry as the druggist kept me waiting, and I had to serve tea at once.”

“But what did you do with the aconitine pills?” demanded Barbara.

“I left the box on the hall table, miss—”

“Great heavens!” Barbara stared at the butler, then without a word she raced up the staircase and disappeared through the open door of Mrs. Brewster's bedroom.

The light from the hall shone through the transom and doorway in sufficient volume to clearly indicate the different pieces of furniture, and Barbara put the pitcher and glass on the bed stand and laid the letter which Grimes had given her on the dressing table, then went slowly into her own bedroom. She could hear voices, which she recognized as those of her sister and Mrs. Brewster, coming from Helen's bedroom, but absorbed in her own thoughts she undressed in the dark and crept into bed just as Mrs. Brewster passed down the hallway and entered her own room. The widow had taken off her evening gown and slippers and donned a becoming wrapper before she discovered the letter lying on the dresser. Drawing up a chair she dropped into it, let down her long dark hair, and settled back in luxuriant comfort against the tufted upholstery before she ran her well-manicured finger under the flap of the envelope. A slip of paper fell into her lap as she took out the contents of the envelope and she let it rest there while scanning the closely typewritten lines on the Metropolis Trust Company stationery.

Dear Mrs. Brewster, she read. Our bank teller, Mr. McDonald, has questioned the genuineness of the signature on the inclosed check. An important business engagement prevents my calling to-night, but please stop at the bank early to-morrow morning.

I feel that you would prefer to have a personal investigation made rather than have us place the matter in the hands of the police.

Yours faithfully,

BENJAMIN A. CLYMER.

The widow read the note a number of times, then bethinking herself, she picked up the canceled check still lying in her lap, and turned it over. Long and intently she studied the signature—the peculiarly characteristic formation of the letter “B” caught and held her attention. As the seconds ticked themselves into minutes she sat immovable, her face as white as the hand on which she had bowed her head.

Across the hall Helen McIntyre tossed from one side to the other in her soft bed; her restless longing to get up was growing stronger and stronger. While Mrs. Brewster's deft fingers and the cooling cologne had stopped the throbbing in her temples, they had brought only temporary relief in their train and not the sleep which Helen craved. She strained her ears to discover the time by the ticking of her clock, but either it was between the half or quarters of an hour, or it had stopped, for no chimes sounded. With a gasp of exasperation, Helen flung back the bed clothes and sat up. Switching on the light by the side of her bed she hunted for a book, but not finding any, she contemplated for a short space of time a pair of rubber-heeled shoes just showing themselves under the edge of a chair. With sudden decision she left the bed and dressed rapidly. It was not until she had put on her rubber-heeled shoes that she paused. Her hesitation, however, was but brief. Stepping to the bureau, she pulled out a lower drawer and running her hand inside, touched a concealed spring. From the cavity thus exposed she took a small automatic pistol, and with a stealthy glance about her, crept from the room.

The library had been vacant fully an hour when a mouse, intent on making a raid on the candy which Barbara had carelessly left lying loose on one of the tables, paused as a faint creaking sound broke the stillness, then as the noise increased, the mouse scurried back to its hole. The noise resembled the turning of rusty hinges and the soft thud of one piece of wood striking another. There was a strained silence, then, from out of the darkness appeared a tiny stream of light directed full on a white envelope bearing a large red seal.

The next instant the envelope was plucked from the hand holding it, and a figure lay crumpled on the floor from the blow of a descending weapon.

It was closely approaching one o'clock in the morning before Mrs. Brewster stirred from her comfortable bedroom chair. Taking up her electric torch, which she kept always by the side of her bed, she walked quickly down the staircase and into the pitch dark library. Directing her torch-light so that she steered a safe course among the chairs and tables, she approached one of the pieces of carved Venetian furniture and reached out her hand to touch a trap-door. As she looked for the spring she was horrified to see a thin stream of blood oozing through the carving until, reaching the letter “B,” it outlined that initial in sinister red.

Scream after scream broke from Mrs. Brewster. She was swaying upon her feet by the time Colonel McIntyre and his daughter Helen reached the library.

“Margaret! What is it?” McIntyre demanded. “Calm yourself, my darling.”

The frenzied woman shook off his soothing hand.

“See, see!” she cried and pointed with her torch.

“She means the Venetian casket,” explained Helen, who had paused before joining them to switch on the light.

Colonel McIntyre gazed in amazement at the piece of furniture; then catching sight of the blood-stain, he raised the small trap-door or peep hole, in the top of the oblong box which stood breast high, supported on a beautifully carved base.

There was a breathless pause; then McIntyre unceremoniously jerked the electric torch from Mrs. Brewster's nervous fingers and turned its rays of the interior of the casket. Stretched at full length lay the figure of a man, and from a wound in his temple flowed a steady stream of blood.

“Good God!” McIntyre staggered back against Helen. “Grimes!”