"Assassin!"

This was the cry which rang out in the stillness of the night, and aroused the interest of one inhabitant of Brakely Square who was awake. Mr. Gregory Farrington, a victim of insomnia, heard the sound, and put down the book he was reading, with a frown. He rose from his easy chair, pulled his velvet dressing gown lightly round his rotund form and shuffled to the window. His blinds were lowered, but these were of the ordinary type, and he stuck two fingers between two of the laths.

There was a moist film on the window through which the street lamps showed blurred and indistinct, and he rubbed the pane clear with the tips of his fingers (he described every action to T. B. Smith afterwards).

Two men stood outside the house. They occupied the centre of the deserted pavement, and they were talking excitedly. Through the closed window Mr. Farrington could hear the staccato rattle of their voices, and by the gesticulations, familiar to one who had lived for many years in a Latin country, he gathered that they were of that breed.

He saw one raise his hand to strike the other and caught the flash of a pistol-barrel excitedly flourished.

"Humph!" said Mr. Farrington.

He was alone in his beautiful house in Brakely Square. His butler, the cook, and one sewing maid and the chauffeur were attending the servants' ball which the Manley-Potters were giving. Louder grew the voices on the pavement.

"Thief!" shrilled a voice in French, "Am I to be robbed of——" and the rest was indistinguishable.

There was a policeman on point duty at the other side of the square. Mr. Farrington's fingers rubbed the glass with greater energy, and his anxious eyes looked left and right for the custodian of the law.

He crept down the stairs, opened the metal flap of the letter-box and listened. It was not difficult to hear all they said, though they had dropped their voices, for they stood at the foot of the steps.

"What is the use?" said one in French. "There is a reward large enough for two—but for him—my faith! there is money to be made, sufficient for twenty. It is unfortunate that we should meet on similar errands, but I swear to you I did not desire to betray you——" The voice sank.

Mr. Farrington chewed the butt of his cigar in the darkness of the hall and pieced together the jigsaw puzzle of this disjointed conversation. These men must be associates of Montague—Montague Fallock, who else?

Montague Fallock, the blackmailer for whom the police of Europe were searching, and individually and separately they had arranged to blackmail him—or betray him.

The fact that T. B. Smith also had a house in Brakely Square, and that T. B. Smith was an Assistant Commissioner of the police, and most anxious to meet Montague Fallock in the flesh, might supply reason enough to the logical Mr. Farrington for this conversation outside his respectable door.

"Yes, I tell you," said the second man, angrily, "that I have arranged to see M'sieur—you must trust me——"

"We go together," said the other, definitely, "I trust no man, least of all a confounded Neapolitan——"

Constable Habit had not heard the sound of quarrelling voices, as far as could be gathered from subsequent inquiry. His statement, now in the possession of T. B. Smith, distinctly says, "I heard nothing unusual."

But suddenly two shots rang out.

"Clack—clack!" they went, the unmistakable sound of an automatic pistol or pistols, then a police whistle shrieked, and P. C. Habit broke into a run in the direction of the sound, blowing his own whistle as he ran.

He arrived to find three men, two undoubtedly dead on the ground, and the third, Mr. Farrington's unpicturesque figure, standing shivering in the doorway of his house, a police whistle at his lips, and his grey velvet dressing-gown flapping in a chill eastern wind.

Ten minutes later T. B. Smith arrived on the scene from his house, to find a crowd of respectable size, half the bedroom windows of Brakely Square occupied by the morbid and the curious, and the police ambulance already on the spot.

"Dead, sir," reported the constable.

T. B. looked at the men on the ground. They were obviously foreigners. One was well, almost richly dressed; the other wore the shabby evening dress of a waiter, under the long ulster which covered him from neck to foot.

The men lay almost head to head. One flat on his face (he had been in this position when the constable found him, and had been restored to that position when the methodical P. C. Habit found that he was beyond human assistance) and the other huddled on his side.

The police kept the crowd at a distance whilst the head of the secret police (T. B. Smith's special department merited that description) made a careful examination. He found a pistol on the ground, and another under the figure of the huddled man, then as the police ambulance was backed to the pavement, he interviewed the shivering Mr. Farrington.

"If you will come upstairs," said that chilled millionaire, "I will tell you all I know."

T. B. sniffed the hall as he entered, but said nothing. He had his olfactory sense developed to an abnormal degree, but he was a tactful and a silent man.

He knew Mr. Farrington—who did not?—both as a new neighbour and as the possessor of great wealth.

"Your daughter——" he began.

"My ward," corrected Mr. Farrington, as he switched on all the lights of his sitting-room, "she is out—in fact she is staying the night with my friend Lady Constance Dex—do you know her?"

T. B. nodded.

"I can only give you the most meagre information," said Mr. Farrington. He was white and shaky, a natural state for a law-abiding man who had witnessed wilful murder. "I heard voices and went down to the door, thinking I would find a policeman—then I heard two shots almost simultaneously, and opened the door and found the two men as they were found by the policeman."

"What were they talking about?"

Mr. Farrington hesitated.

"I hope I am not going to be dragged into this case as a witness?" he asked, rather than asserted, but received no encouragement in the spoken hope from T. B. Smith.

"They were discussing that notorious man, Montague Fallock," said the millionaire; "one was threatening to betray him to the police."

"Yes," said T. B. It was one of those "yesses" which signified understanding and conviction.

Then suddenly he asked:

"Who was the third man?"

Mr. Farrington's face went from white to red, and to white again.

"The third man?" he stammered.

"I mean the man who shot those two," said T. B., "because if there is one thing more obvious than another it is that they were both killed by a third person. You see," he went on, "though they had pistols neither had been discharged—that was evident, because on each the safety catch was raised. Also the lamp-post near which they stood was chipped by a bullet which neither could have fired. I suggest, Mr. Farrington, that there was a third man present. Do you object to my searching your house?"

A little smile played across the face of the other.

"I haven't the slightest objection," he said. "Where will you start?"

"In the basement," said T. B.; "that is to say, in your kitchen."

The millionaire led the way down the stairs, and descended the back stairway which led to the domain of the absent cook. He turned on the electric light as they entered.

There was no sign of an intruder.

"That is the cellar door," indicated Mr. Farrington, "this the larder, and this leads to the area passage. It is locked."

T. B. tried the handle, and the door opened readily.

"This at any rate is open," he said, and entered the dark passageway.

"A mistake on the part of the butler," said the puzzled Mr. Farrington. "I have given the strictest orders that all these doors should be fastened. You will find the area door bolted and chained."

T. B. threw the rays of his electric torch over the door.

"It doesn't seem to be," he remarked; "in fact, the door is ajar."

Farrington gasped.

"Ajar?" he repeated. T. B. stepped out into the well of the tiny courtyard. It was approached from the street by a flight of stone stairs.

T. B. threw the circle of his lamp over the flagged yard. He saw something glittering and stooped to pick it up. The object was a tiny gold-capped bottle such as forms part of the paraphernalia in a woman's handbag.

He lifted it to his nose and sniffed it.

"That is it," he said.

"What?" asked Mr. Farrington, suspiciously.

"The scent I detected in your hall," replied T. B. "A peculiar scent, is it not?" He raised the bottle to his nose again. "Not your ward's by any chance?"

Farrington shook his head vigorously.

"Doris has never been in this area in her life," he said; "besides, she dislikes perfumes."

T. B. slipped the bottle in his pocket.

Further examination discovered no further clue as to the third person, and T. B. followed his host back to the study.

"What do you make of it?" asked Mr. Farrington.

T. B. did not answer immediately. He walked to the window and looked out. The little crowd which had been attracted by the shots and arrival of the police ambulance had melted away. The mist which had threatened all the evening had rolled into the square and the street lamps showed yellow through the dingy haze.

"I think," he said, "that I have at last got on the track of Montague Fallock."

Mr. Farrington looked at him with open mouth.

"You don't mean that?" he asked incredulously.

T. B. inclined his head.

"The open door below—the visitor?" jerked the stout man, "you don't think Montague Fallock was in the house to-night?"

T. B. nodded again, and there was a moment's silence.

"He has been blackmailing me," said Mr. Farrington, thoughtfully, "but I don't think——"

The detective turned up his coat collar preparatory to leaving.

"I have a rather unpleasant job," he said. "I shall have to search those unfortunate men."

Mr. Farrington shivered. "Beastly," he said, huskily.

T. B. glanced round the beautiful apartment with its silver fittings, its soft lights and costly panellings. A rich, warm fire burnt in an oxidized steel grate. The floor was a patchwork of Persian rugs, and a few pictures which adorned the walls must have been worth a fortune.

On the desk there was a big photograph in a plain silver frame—the photograph of a handsome woman in the prime of life.

"Pardon me," said T. B., and crossed to the picture, "this is——"

"Lady Constance Dex," said the other, shortly—"a great friend of mine and my ward's."

"Is she in town?"

Mr. Farrington shook his head.

"She is at Great Bradley," he said; "her brother is the rector there."

"Great Bradley?"

T. B.'s frown showed an effort to recollect something.

"Isn't that the locality which contains the Secret House?"

"I've heard something about the place," said Mr. Farrington with a little smile.

"C. D.," said the detective, making for the door.

"What?"

"Lady Constance Dex's initials, I mean," said T. B.

"Yes—why?"

"Those are the initials on the gold scent bottle, that is all," said the detective. "Good night."

He left Mr. Farrington biting his finger nails—a habit he fell into when he was seriously perturbed.