did. Then peace and quiet reigned until half past eleven, when I heard

the shot in Chet’s room.”

“How long was this interregnum of quietude?” asked Vance.

“Well, mother generally ends her daily criticism of the family around ten-thirty; so I’d say the quietude lasted about an hour.”

“And during that time you do not recall hearing a slight shuffling sound in the hall? Or a door closing softly?”

The girl shook her head indifferently, and took another cigarette from a small amber case she carried in her sweater-pocket.

“Sorry, but I didn’t. That doesn’t mean, though, that people couldn’t have been shuffling and shutting doors all over the place. My room’s at the rear, and the noises on the river and in 52d Street drown out almost anything that’s going on in the front of the house.”

Vance had gone to her and held a match to her cigarette.

“I say, you don’t seem in the least worried.”

“Oh, why worry?” She made a gesture of resignation. “If anything is to happen to me, it’ll happen, whatever I do. But I don’t anticipate an immediate demise. No one has the slightest reason for killing me—unless, of course, it’s some of my former bridge partners. But they’re all harmless persons who wouldn’t be apt to take extreme measures.”

“Still”—Vance kept his tone inconsequential—“no one apparently had any reason for harming your two sisters or your brother.”

“On that point I couldn’t be altogether lucid. We Greenes don’t confide in one another. There’s a beastly spirit of distrust in this ancestral domain. We all lie to each other on general principles. And as for secrets! Each member of the family is a kind of Masonic Order in himself. Surely there’s some reason for all these shootings. I simply can’t imagine any one indulging himself in this fashion for the mere purpose of pistol practice.”

She smoked a moment pensively, and went on:

“Yes, there must be a motive back of it all—though for the life of me I can’t suggest one. Of course Julia was a vinegary, unpleasant person, but she went out very little, and worked off her various complexes on the family. And yet, she may have been leading a double life for all I know. When these sour old maids break loose from their inhibitions I understand they do the most utterly utter things. But I just can’t bring my mind to picture Julia with a bevy of jealous Romeos.” She made a comical grimace at the thought. “Ada, on the other hand, is what we used to call in algebra an unknown quantity. No one but dad knew where she came from, and he would never tell. To be sure, she doesn’t get much time to run around—mother keeps her too busy. But she’s young and good-looking in a common sort of way”—there was a tinge of venom in this remark—“and you can’t tell what connections she may have formed outside the sacred portals of the Greene mansion.—As for Chet, no one seemed to love him passionately. I never heard anybody say a good word for him but the golf pro at the club, and that was only because Chet tipped him like a _parvenu_. He had a genius for antagonizing people. Several motives for the shooting might be found in his past.”

“I note that you’ve changed your ideas considerably in regard to the culpability of Miss Ada.” Vance spoke incuriously.

Sibella looked a little shamefaced.

“I did get a bit excited, didn’t I?” Then a defiance came into her voice. “But just the same, she doesn’t belong here. And she’s a sneaky little cat. She’d dearly love to see us all nicely murdered. The only person that seems to like her is cook; but then, Gertrude’s a sentimental German who likes everybody. She feeds half the stray cats and dogs in the neighborhood. Our rear yard is a regular pound in summer.”

Vance was silent for a while. Suddenly he looked up.

“I gather from your remarks, Miss Greene, that you now regard the shootings as the acts of some one from the outside.”

“Does any one think anything else?” she asked, with startled anxiety. “I understand there were footprints in the snow both times we were visited. Surely they would indicate an outsider.”

“Quite true,” Vance assured her, a bit overemphatically, obviously striving to allay whatever fears his queries may have aroused in her. “Those footprints undeniably indicate that the intruder entered each time by the front door.”

“And you are not to have any uneasiness about the future, Miss Greene,” added Markham. “I shall give orders to-day to have a strict guard placed over the house, front and rear, until there is no longer the slightest danger of a recurrence of what has taken place here.”

Heath nodded his unqualified approbation.

“I’ll arrange for that, sir. There’ll be two men guarding this place day and night from now on.”

“How positively thrilling!” exclaimed Sibella; but I noticed a strange reservation of apprehension in her eyes.

“We won’t detain you any longer, Miss Greene,” said Markham, rising. “But I’d greatly appreciate it if you would remain in your room until our inquiries here are over. You may, of course, visit your mother.”

“Thanks awf’ly, but I think I’ll indulge in a little lost beauty sleep.” And she left us with a friendly wave of the hand.

“Who do you want to see next, Mr. Markham?” Heath was on his feet, vigorously relighting his cigar.

But before Markham could answer Vance lifted his hand for silence, and leaned forward in a listening attitude.

“Oh, Sproot!” he called. “Step in here a moment.”

The old butler appeared at once, calm and subservient, and waited with a vacuously expectant expression.

“Really, y’ know,” said Vance, “there’s not the slightest need for you to hover solicitously amid the draperies of the hallway while we’re busy in here. Most considerate and loyal of you; but if we want you for anything we’ll ring.”

“As you desire, sir.”

Sproot started to go, but Vance halted him.

“Now that you’re here you might answer one or two questions.”

“Very good, sir.”

“First, I want you to think back very carefully, and tell me if you observed anything unusual when you locked up the house last night.”

“Nothing, sir,” the man answered promptly. “If I had, I would have mentioned it to the police this morning.”

“And did you hear any noise or movement of any kind after you had gone to your room? A door closing, for instance?”

“No, sir. Everything was very quiet.”

“And what time did you actually go to sleep?”

“I couldn’t say exactly, sir. Perhaps about twenty minutes past eleven, if I may venture to make a guess.”

“And were you greatly surprised when Miss Sibella woke you up and told you a shot had been fired in Mr. Chester’s room?”

“Well, sir,” Sproot admitted, “I was somewhat astonished, though I endeavored to conceal my emotions.”

“And doubtless succeeded admirably,” said Vance dryly. “But what I meant was this: did you not anticipate something of the kind happening again in this house, after the other shootings?”

He watched the old butler sharply, but the man’s lineaments were as arid as a desert and as indecipherable as an expanse of sea.

“If you will pardon me, sir, for saying so, I don’t know precisely what you mean,” came the colorless answer. “Had I anticipated that Mr. Chester was to be done in, so to speak, I most certainly would have warned him. It would have been my duty, sir.”

“Don’t evade my question, Sproot.” Vance spoke sternly. “I asked you if you had any idea that a second tragedy might follow the first.”

“Tragedies very seldom come singly, sir, if I may be permitted to say so. One never knows what will happen next. I try not to anticipate the workings of fate, but I strive to hold myself in readiness——”

“Oh, go away, Sproot—go quite away,” said Vance. “When I crave vague rhetoric I’ll read Thomas Aquinas.”

“Yes, sir.” The man bowed with wooden courtesy, and left us.

His footsteps had scarcely died away when Doctor Doremus strode in jauntily.

“There’s your bullet, Sergeant.” He tossed a tiny cylinder of discolored lead on the drawing-room table. “Nothing but dumb luck. It entered the fifth intercostal space and travelled diagonally across the heart, coming out in the post-axillary fold at the anterior border of the trapezius muscle, where I could feel it under the skin; and I picked it out with my pen-knife.”

“All that fancy language don’t worry me,” grinned Heath, “so long’s I got the bullet.”

He picked it up and held it in the palm of his hand, his eyes narrowed, his mouth drawn into a straight line. Then, reaching into his waistcoat pocket, he took out two other bullets, and laid them beside the first. Slowly he nodded, and extended the sinister exhibits to Markham.

“There’s the three shots that were fired in this house,” he said. “They’re all .32-revolver bullets—just alike. You can’t get away from it, sir: all three people here were shot with the same gun.”