"Indeed?" said Angus; "is there something they can't do?"
"Yes," replied Smythe coolly; "they can't tell me who left those threatening letters at my flat."
The man's motor was small and swift like himself; in fact, like his domestic service, it was of his own invention. If he was an advertising quack, he was one who believed in his own wares. The sense of something tiny and flying was accentuated as they swept up long white curves of road in the dead but open daylight of evening. Soon the white curves came sharper and dizzier; they were upon ascending spirals, as they say in the modern religions. For, indeed, they were cresting a corner of London which is almost as precipitous as Edinburgh, if not quite so picturesque. Terrace rose above terrace, and the special tower of flats they sought, rose above them all to almost Egyptian height, gilt by the level sunset. The change, as they turned the corner and entered the crescent known as Himylaya Mansions, was as abrupt as the opening of a window; for they found that pile of flats sitting above London as above a green sea of slate. Opposite to the mansions, on the other side of the gravel crescent, was a bushy enclosure more like a steep hedge or dyke than a garden, and some way below that ran a strip of artificial water, a sort of canal, like the moat of that embowered fortress. As the car swept round the crescent it passed, at one corner, the stray stall of a man selling chestnuts; and right away at the other end of the curve, Angus could see a dim blue policeman walking slowly. These were the only human shapes in that high suburban solitude; but he had an irrational sense that they expressed the speechless poetry of London. He felt as if they were figures in a story.
The little car shot up to the right house like a bullet, and shot out its owner like a bomb shell. He was immediately inquiring of a tall commissionaire in shining braid, and a short porter in shirt sleeves, whether anybody or anything had been seeking his apartments. He was assured that nobody and nothing had passed these officials since his last inquiries; whereupon he and the slightly bewildered Angus were shot up in the lift like a rocket, till they reached the top floor.
"Just come in for a minute," said the breathless Smythe. "I want to show you those Welkin letters. Then you might run round the corner and fetch your friend." He pressed a button concealed in the wall, and the door opened of itself.
It opened on a long, commodious ante-room, of which the only arresting features, ordinarily speaking, were the rows of tall half-human mechanical figures that stood up on both sides like tailors' dummies. Like tailors' dummies they were headless; and like tailors' dummies they had a handsome unnecessary humpiness in the shoulders, and a pigeon-breasted protuberance of chest; but barring this, they were not much more like a human figure than any automatic machine at a station that is about the human height. They had two great hooks like arms, for carrying trays; and they were painted pea-green, or vermilion, or black for convenience of distinction; in every other way they were only automatic machines and nobody would have looked twice at them. On this occasion, at least, nobody did. For between the two rows of these domestic dummies lay something more interesting than most of the mechanics of the world. It was a white, tattered scrap of paper scrawled with red ink; and the agile inventor had snatched it up almost as soon as the door flew open. He handed it to Angus without a word. The red ink on it actually was not dry, and the message ran, "If you have been to see her to-day, I shall kill you."
There was a short silence, and then Isidore Smythe said quietly, "Would you like a little whisky? I rather feel as if I should."
"Thank you; I should like a little Flambeau," said Angus, gloomily. "This business seems to me to be getting rather grave. I'm going round at once to fetch him."
"Right you are," said the other, with admirable cheerfulness. "Bring him round here as quick as you can."
But as Angus closed the front door behind him he saw Smythe push back a button, and one of the clockwork images glided from its place and slid along a groove in the floor carrying a tray with syphon and decanter. There did seem something a trifle weird about leaving the little man alone among those dead servants, who were coming to life as the door closed.
Six steps down from Smythe's landing the man in shirt sleeves was doing something with a pail. Angus stopped to extract a promise, fortified with a prospective bribe, that he would remain in that place until the return with the detective, and would keep count of any kind of stranger coming up those stairs. Dashing down to the front hall he then laid similar charges of vigilance on the commissionaire at the front door, from whom he learned the simplifying circumstances that there was no back door. Not content with this, he captured the floating policeman and induced him to stand opposite the entrance and watch it; and finally paused an instant for a pennyworth of chestnuts, and an inquiry as to the probable length of the merchant's stay in the neighbourhood.
The chestnut seller, turning up the collar of his coat, told him he should probably be moving shortly, as he thought it was going to snow. Indeed, the evening was growing grey and bitter, but Angus, with all his eloquence, proceeded to nail the chestnut man to his post.
"Keep yourself warm on your own chestnuts," he said earnestly. "Eat up your whole stock; I'll make it worth your while. I'll give you a sovereign if you'll wait here till I come back, and then tell me whether any man, woman, or child has gone into that house where the commissionaire is standing."
He then walked away smartly, with a last look at the besieged tower.
"I've made a ring round that room, anyhow," he said. "They can't all four of them be Mr. Welkin's accomplices."
Lucknow Mansions were, so to speak, on a lower platform of that hill of houses, of which Himylaya Mansions might be called the peak. Mr. Flambeau's semi-official flat was on the ground floor, and presented in every way a marked contrast to the American machinery and cold hotel-like luxury of the flat of the Silent Service. Flambeau, who was a friend of Angus, received him in a rococo artistic den behind his office, of which the ornaments were sabres, harquebuses, Eastern curiosities, flasks of Italian wine, savage cooking-pots, a plumy Persian cat, and a small dusty-looking Roman Catholic priest, who looked particularly out of place.
"This is my friend Father Brown," said Flambeau. "I've often wanted you to meet him. Splendid weather, this; a little cold for Southerners like me."
"Yes, I think it will keep clear," said Angus, sitting down on a violet-striped Eastern ottoman.
"No," said the priest quietly, "it has begun to snow."
And, indeed, as he spoke, the first few flakes, foreseen by the man of chestnuts, began to drift across the darkening windowpane.
"Well," said Angus heavily. "I'm afraid I've come on business, and rather jumpy business at that. The fact is, Flambeau, within a stone's throw of your house is a fellow who badly wants your help; he's perpetually being haunted and threatened by an invisible enemy—a scoundrel whom nobody has even seen." As Angus proceeded to tell the whole tale of Smythe and Welkin, beginning with Laura's story, and going on with his own, the supernatural laugh at the corner of two empty streets, the strange distinct words spoken in an empty room, Flambeau grew more and more vividly concerned, and the little priest seemed to be left out of it, like a piece of furniture. When it came to the scribbled stamp-paper pasted on the window, Flambeau rose, seeming to fill the room with his huge shoulders.
"If you don't mind," he said, "I think you had better tell me the rest on the nearest road to this man's house. It strikes me, somehow, that there is no time to be lost."
"Delighted," said Angus, rising also, "though he's safe enough for the present, for I've set four men to watch the only hole to his burrow."
They turned out into the street, the small priest trundling after them with the docility of a small dog. He merely said, in a cheerful way, like one making conversation, "How quick the snow gets thick on the ground."
As they threaded the steep side streets already powdered with silver, Angus finished