It was half-past eleven on the night of Wednesday, April 14th, when the well-known red limousine of Mr. Maverick Narkom, superintendent of Scotland Yard, came abruptly to the head of Mulberry Lane, which, as you may possibly know, is a narrow road skirting one of the loneliest and wildest portions of Wimbledon Common.

Lennard, the chauffeur, put on the brake with such suddenness that the car seemed actually to rise from the earth, performed a sort of buzzing and snorting semicircle, and all but collided with the rear wall of Wuthering Grange before coming to a halt in the narrow road space which lay between that wall and the tree-fringed edge of the great Common.

Under ordinary circumstances one might as soon have expected to run foul of a specimen of the great auk rearing a family in St. Paul's churchyard, as to find Mr. Narkom's limousine in the neighbourhood of Mulberry Lane at any hour of the day or the night throughout the whole cycle of the year.

For a reason which will be made clear in the course of events, however, the superintendent had been persuaded to go considerably out of his way before returning to town after mingling duty with pleasure in taking part in the festivities attendant upon the coming of age of his friend Sir Philip Clavering's son and heir, and, incidentally, in seeing, too, that Petrie and Hammond, two of his sergeants, kept a watchful eye upon the famous Clavering service of gold plate which had been brought out of the bank vault for the occasion.

All three were sitting serenely back among the cushions of the limousine at the period when Lennard brought it to this abrupt and startling halt, the result of which was to fairly jerk them out of their seats and send them sprawling over one another in a struggling heap.

There was a moment of something like absolute confusion, for mist and darkness enveloped both the road and the Common, and none of the three could see anything from the windows of the car which might decide whether they had collided with some obstruction or were hovering upon the brink of some dangerous and unexpected pitfall.

Nor were their fears lessened by perceiving—through the glass screen—that Lennard had started up from his seat, and, with a hastily produced electric torch in one upraised hand, was leaning forward and wildly endeavouring to discern something through the all-enfolding mist. Mr. Narkom hastily unlatched the door and leaned out.

"What is it? What's gone wrong?" he inquired in the sharp staccato of excitement. "Anything amiss?"

"Lord, yessir! I heard a shot and a cry. A pistol shot ... and a police whistle ... and a cry of murder, sir. Up the lane ahead of us!" began Lennard, in a quaking voice; then he uttered a cry of fright, for, of a sudden, the darkness was riven by the screaming note of a police whistle—of two police whistles in fact: shrilling appeal and answer far up the lonely lane.

Hard on this came a man's voice shouting: "Head him off there, whoever you are! Don't let him get by you. Look sharp! He's making for the railway arch!"

"All right, mate. I'm here!" another male voice flung back. "He won't get past me, the blighter!"

Instantly there struck out the swift-measured sound of heavily shod feet racing at top speed up the mist-shrouded lane, and rapidly increasing the distance between the unseen runner and the standing limousine.

No need to tell either Narkom or his men that the man whose steps they heard was a constable, for there is a distinctive note, to ears that are trained, rung out by the heavy, cumbersome boots which folly accords to the British policeman.

Catching the ring of that telltale note now, Narkom shouted out at the top of his voice: "All right, Constable! Stick to him! Help coming!"

Then with a word of command to Lennard he pulled in his head, slammed the door, and the chauffeur, dropping back to his seat, threw open the clutch and sent the limousine bounding up the lane at a fifty-mile clip.

To-night, with the trees shadowing it and the mist crowding in, shoulder high, from the adjacent Common, the lane was a mere dark funnel; but to Lennard, whose boyhood had been passed within hailing distance of the place, it possessed no mysteries that the night or the vapour could hide.

He knew that it ran on for some seven or eight hundred feet, with the high brick wall which marked the rear boundary of Wuthering Grange on one side of it and straggling trees and matted gorse bushes shutting it in on the other, until it dipped down a steadily increasing incline, and ran straightway through an old brick-walled, brick-roofed arch of a long-abandoned Wimbledon Loop line.

Some two hundred feet upon the other side of this it divided into a sort of "Y," one branch swerving to the left forming a right of way across the meadows to the public highway, whilst the other struck out over the Common to the right, crossed Beverly Brook, and merged at length into the road which leads to Coombe Wood, and thence, through picturesque ways, to Kingston and the river.

The limousine took those seven or eight hundred feet between the head of the lane and the old railway arch at such a stupendous pace that it seemed to have no more than started before the distance was eaten up and it came to halt again; but this time, in such a din and babel of struggling and shouting that Lennard seemed to have reached the very gateway of Sheol.

Narkom and his men were out of the vehicle almost as the brake fell into place, and clicking their electric pocket torches into sudden flame, rushed headlong into the black opening of the arch, into which they had taken but half a dozen steps, when they came upon a startling sight.

Snarling and yapping like a couple of fighting dogs and crying out in concert: "Got you, you blighter! Got you fast!" were two men, locked tight in each other's arms, reeling and swaying—one wearing the official badge of an appointed Common keeper, the other in the helmet and tunic of an ordinary constable.

"Lend a hand, gov'ner, for Gawd's sake!" rapped out the former. "Name's Mawson, sir—keeper on the Common— Number four, sir. Got the blackguard! Murder, sir—got him red handed!"

"Good Lord!" little more than gulped the man he held.

The two pairs of gripping hands dropped, the struggling figures fell apart, and the two men who but an instant before had been locked in an angry embrace stood staring at each other in open-mouthed amazement.

"What kind of a game is this?" demanded Narkom, as with his allies he crowded forward. "You two people are paid to keep the peace, not to break it, dash you!"

"My word!" exclaimed the Common keeper, finding his voice suddenly. "A copper, is it?—a copper! when I thought.... Gawd's truth, Constable, wot have you done with him? He run in here with me on his blessed heels. You didn't let him get past you, did you?"

"No fear!" snapped out the constable indignantly. "I stood here waiting—waiting and shouting to you—until you ran smack into my blessed arms; and if anybody but you come in your side of the arch, he never come out o' mine, I'll take my solemn oath!"

"Then where's he gone? Wot's become of him?" shouted the Common keeper excitedly. "I tell you I was on the very heels of him from the moment I first whistled and called out to you to head him off. I could a-most have touched him when he dashed in here; and—and his footsteps never stopped soundin' for one second the whole blessed time. Murder is wot he's done—murder!—and I've been on his heels from the very moment he fired the shot."

Narkom and his allies lost not an instant in revealing their identity and displaying their insignia of office to the two men.

"Murder is it, Keeper?" exclaimed the superintendent, remembering all at once what Lennard had said about hearing the cry and the shot. "When and how? Lead me to the body."

"Lor' bless you, sir, I aren't 'ad no time nor chanct to look after any body," replied the keeper. "All's I can tell you is that I was out there in my shelter on the Common when I heard the first cry—like as some one was callin' for help whiles some one else had 'em by the windpipe, sir; so I dashes out and cuts through the mist and gorse as fast as my blessed legs could carry me. Jist as I gets to the edge of the lane, sir, 'Bang!' goes a revolver shot jist 'arf a dozen feet in front of me, and a man, wot I couldn't see 'ide nor 'air of on account of the mist, nicks out o' somewheres, and cuts off down the lane like a blessed race 'orse. I outs with me whistle and blows it as 'ard as I could, and cuts off after him. He never stopped runnin' for a blessed instant. He never doubled on me, never turned to the right nor to the left, gov'ner, but jist dashes into this arch—straight in front of me, sir, and me running on almost within reachin' distance, until I runs smack into the arms of this constable here, and grabs him, thinkin' I'd got my man for sure. Wherever he's got to since, I tell you he come in here, sir—smack in!—and me after him; and if he didn't get past the constable——"

"He didn't— I've told you so once, and I'll stick to it!" interrupted the constable himself, with some show of heat. "What do you take me for—an old woman? Look here, Mr. Narkom, sir, my name's Mellish. It's true I've only been on the force a little over a week, sir, but my sergeant will tell you I've got my wits about me and aren't in the least likely to let a man slip past me in the manner that this chap thinks. Nothing went past me—nothing the size of a cat, let alone a man, sir—and if the party in question really did come in here——"

"I'll soon settle that question!" rapped in Narkom sharply.

He flung a hurried command to Lennard, waved Petrie and Hammond aside, and an instant later the limousine moved swiftly up out of the mist until its bulk filled the entrance of the arch and its blazing acetylene lamps were sweeping it with light from end to end. Smooth as a rifle bore, its damp walls and curving roof shone out in the sudden glare—not a brick displaced, not a crevice big enough to shelter a rat much less a human being—and of the man the Common keeper had been chasing, not a sign nor a trace anywhere!

"Whatever the fellow did or wherever he went, he can't have gone far, so look sharp, my lads!" commanded Narkom. "If we're quick we're sure to nab him. Come along, Constable, come along, Keeper. Lennard, you stop where you are and guard the exit from the arch, so if he doubles on us he can't get by you!"

"Right you are, sir!" responded Lennard, as the superintendent and the four men made a dash toward that end of the arch through which the keeper was so positive the fugitive had come.

"I say, Mr. Narkom!" he added, raising his voice and shouting after them. "Eyes sharp to the left, all of you, when you get outside this arch. Know the neighbourhood like a book, sir. Lane forks out into a 'Y' after you get about fifty yards on. Branches off on the left where there's an old house called Gleer Cottage, sir, that hasn't been tenanted for years and years. Walled garden—tool house—stable. Great place for man to hide, sir!"

"Good boy! Thanks!" flung back Narkom. "Come on, my lads! Lively!"

Then they swung out of the arch with a rush, and the last that Lennard saw of them before the shrouding mist took them and blotted them from his view, they were pelting up the lane at top speed and making headlong for the branching "Y" to which he had directed them, their footsteps sounding on the moist surface of the road and their electric torches emitting every now and again a spark like a glowworm flashing.

Five minutes passed—the click of their flying steps had dropped off into silence; the flash of their torches had vanished in the distance and the mist; even the blurred sound of their excited voices was stilled; and neither ear nor eye could now detect anything but the soft drip of the moisture from the roof of the arch and the white oblivion of the close-pressing, ever-thickening mist.

Still he sat there, waiting—alert, watchful, keen—looking straight before him and keeping a close watch on the unobstructed end of the miniature tunnel whose entire length was still flooded with the glare from the motor's lamps. If a mouse had crawled down its damp walls he must have seen it; if even so much as a shadow had come up out of that wilderness of mist and crept into the place, he must have detected, it. But there was nothing; neither man nor beast, neither shade nor shadow; only the loneliness and the mist and the soft "plick-plick!" of the dropping moisture.

The five minutes became eight, ten, a dozen, without the slightest change in anything. Then, all of a sudden, Lennard's tense nerves gave a sort of jump and a swift prickle flashed up his spine and through his hair. A sound had come—a rustle—a step—a movement. Not from the direction in which he was looking, however, but from the lane beyond the arch and behind the limousine.

He jumped to his feet and rising on tiptoe on his driver's seat flashed the light of his electric torch back over the top of the vehicle; what he saw took all the breath out of him and set his heart and pulses hammering furiously.

Against that thick blanket of mist the penetrating power of the torch's gleam was so effectually blunted that it could do nothing more than throw a pale, weak circle of light a few feet into the depths of a crowding vapour, leaving all beyond and upon either side doubly dark in contrast.

Yet as the light streamed out and flung that circle into the impinging mist, there moved across it the figure of a woman, young and fair, with a scarf of lace thrown over her head, from beneath which fell a glory of unbound hair, thick and lustrous, over shoulders that were wrapped in ermine—ermine in mid-April!

A woman! Here! At this hour! In this time of violence and evil doing! The thing was so uncanny, so unnatural, so startlingly unexpected, that Lennard's head swam.

She was gone so soon—just glimmering across the circle of light and then vanishing into the mist as suddenly as she had appeared—that for a moment or two he lost his nerve and his wits, and ducked down under the screen of the motor's top, remembering all the tales he had ever heard of ghosts and apparitions, and, in a moment of folly, half believing he had looked upon one. But of a sudden his better sense asserted itself, and realizing that for a woman—any woman, no matter how dressed, no matter how young and fair and good to look upon—to be moving stealthily about this place, at this hour, when there was talk of murder, was at least suspicious, he laid hands upon the wheel, and being unable to turn the vehicle in the arch and go after her, put on full power and went after Narkom and his men. A swift whizz carried him through the arch and up the lane, and, once in the open, he laid hand upon the bulb of the motor horn and sent blast after blast hooting through the stillness, shouting at the top of his voice as he scorched over the ground:

"Mr. Narkom! Mr. Narkom! This way, sir, this way! This way!"