It was at a little past nine in the evening that I next saw Hewitt. He came into my rooms in an incongruous get-up. He wore corduroy trousers, a very dirty striped jersey, a particularly greasy old jacket, and a twisted neckcloth; but over all was an excellent overcoat, and on his head a tall hat of high polish.

"Brought to me by Kerrett," he said, in explanation of the hat and overcoat. "He's been waiting with them for a long time in a court by Milford Lane. A good hat and overcoat will cover anything, and I preferred to enter this building in my own character. I've been wearing that this afternoon," and he pulled out of his pocket an old peaked cap with ear-pieces tied over the top.

"You mustn't bring your best clothes," he went on, "or you'll spoil them scrambling about boats and groping in ditches. I have done my ditch-groping for the day, and I'm going to change. You had best be putting on older things while I get into newer."

"What sort of place is this Channel Marsh?" I asked.

"Well, I should think there must be a great many better places to spend a night in. It must be the dreariest, wettest flat within many miles of London, and I should like to see the portrait of the man who had the idea of building a house there. For a house there is, or rather the ruins of it—deserted for years, and half carried away by rats and people who wanted slates and firewood and water pipes."

"Is that the place where you intend waiting to-night?"

"It is. I haven't examined it nearly so closely as I should like, for fear of raising a scare. Channel Marsh is almost an island, with a narrow neck of an entrance at each end. A foot-track runs the whole length, and a person in the ruined house can easily see anybody entering the Marsh from either end. For that reason I reconnoitred from a boat—the boat you will go in to-night. I think it is the very dirtiest old tub I ever saw, so that it suited my rig out. I discovered it at a wharf some little way down the river, and I paid a shilling for the hire of it. Channel Marsh is banked a bit on one side, and I crept up under cover of the bank. I learned very little, beyond the general lie of the land, because I was so mighty cautious. I judged it better to be content with half an examination, rather than drive away the game. And even as it is I've an idea I have been seen. I lay up among some reeds till dark, but after that I am sure there was somebody on the Marsh—and skulking, too, like me. So after waiting and scouting for a little I gave it up and paddled quietly back."

"But look here, Hewitt," I said, "this seems a bit mad. Why go and risk yourself as you talk of doing? You believe Mayes will be there, at the ruin, or will come there at twelve. Very well, then, why can't the police send enough men to surround the place and capture him for certain?"

Hewitt smiled and shook his head. "My dear Brett," he said, "you haven't seen the place, and I have. It will be hard enough job for you and Plummer to get near the spot unobserved, guided by a man who knows every inch. A trampling crowd of policemen would have as much chance as a herd of elephants, and on such light nights as we are having now they would be seen a mile off. And who knows what scouts he may have out? No, as I say, it will be a great piece of luck if you get through unobserved as it is, and even now I'm not perfectly certain that I couldn't do best alone. However, arrangements are made now, and you are coming, three of you."

"Then what are the arrangements?" I asked.

"Just these. You are to leave here first. Make the best of your way to Mile End Gate, where an old inn stands in the middle of the road. Go to the corner of the turning opposite this, at the south side of the road. At eleven o'clock a four-wheeler will drive up, with Plummer and one of his men in it. The man is one who knows all the geography of Channel Marsh, and he also knows exactly where to find the boat I used to-day. You will drive to a little way beyond Bow Bridge, and then Plummer's man will lead you to the boat. You had better scull and leave the others to look out. They will know what to do. You will pull along to a place where you can watch till you see me coming on to the Marsh by the path. As soon as you see me you will slip quietly along to a place the policeman will show you, close to the ruin, and watch again. That's all. I don't know whether or not you think it worth while to take a pistol. I certainly shall; but then I'm most likely to want it. Plummer will have one."

I thought it well worth while, and I took my regulation "Webley"—a relic of my old Volunteer captaincy. Then, by way of the underground railway, I gained the neighbourhood of Mile End, and interested myself about its back streets till the time approached to look for Plummer's cab.

Plummer was more than punctual—indeed, he was two or three minutes before his time. The cab drew near the kerb and scarcely stopped, so quickly did I scramble in.

"Good," said Plummer; "we're well ahead of time. Mr. Hewitt quite right?"

"Yes," I said. "I left him so an hour and a half ago at his office." And we sat silent while the cab rattled and rumbled over the stony road to Bow Bridge, and the shopkeepers on the way put up their shutters and extinguished their lights.

Bow Bridge was reached and passed, and presently we stopped the cab and alighted. Here Styles, Plummer's man, took the lead, and a little way farther along the road we turned into a dark and muddy lane on the left. We floundered through this for some hundred and fifty yards or so, and then suddenly drew in at an opening on the right. Here we stood for a few moments while our guide groped his way down toward the muddy water we could smell, rather than see, a little way before us.

There were a few broken steps and a broad black thing which was the boat. We got into it as silently as we could manage, and cast off. It was a clumsy, broad-beamed, leaky old conveyance, and that it was as dirty as Hewitt had described it I could feel as I groped for the sculls and got them out. The night was light and dark by turns—changing with the clouds. We shipped the rudder, and Styles steered, or I should probably have run ashore more than once, for the banks were not always distinct, and the channel was narrow and dark. We passed the black forms of several factories with tall chimneys, and then drew out among the Marshes, flat and grey, with wisps of mist lying here and there. So we went in silence for a while, till at last we drew in against the bank on the left and laid hold by a post at a landing-place.

"This is the Channel Marsh," whispered Styles, as we climbed cautiously ashore. "We can't see the house very well from here, but there's where Mr. Hewitt will come through."

Looking over the top of the low bank, we could discern a path which traversed the length of the marsh, entering it by a broken gate at a neck of land which we must have passed on our way. Here we crouched and waited. We had heard the half-hour struck on some distant clock soon after entering the boat, and now we waited anxiously for the three-quarters. So long did the time seem to my excited perceptions that I had quite decided that the clock must have stopped, or, at any rate, did not chime quarters, when at last the strokes came, distant and plaintive, over the misty flats.

"A quarter of an hour," Plummer remarked. "He won't be a minute late, nor a minute too early, from what I know of him. How long will it take him from that gate to the ruin?"

"Eight or nine minutes, good," Styles answered.

"Then we shall see him in seven minutes or six minutes, as the case may be," Plummer rejoined in the same low tones.

Slowly the minutes dragged, with not a sound about us save the sucking and lapping of the muddy river and the occasional flop of a water-rat. The dark clouds were now fewer, and the moon was high and only partially obscured by the thinner clouds that traversed its face. More than once I fancied a sound from the direction of the ruin, and then I doubted my fancy; when at last there was a sound indeed, but from the opposite direction, and in a moment we saw Hewitt, muffled close about the neck, walking briskly up the path.

We regained the boat with all possible speed and silence, and I pulled my best, regardless of my stiff wrist. During our watch I had had time to perceive the wisdom of the arrangements which had been made. We had been watching from a place fairly out of sight from the ruin, yet sufficiently near it to be able to reach its neighbourhood before Hewitt; and certainly it was better to approach the actual spot at the same time as Hewitt himself, for then, if he were being watched for, the attention of the watcher would be diverted from us.

Presently we reached the reed-bed that Hewitt had spoken of, and I could see a sort of little creek or inlet. Here I ceased to pull, and Styles cautiously punted us into the creek with one of the sculls. The boat grounded noiselessly in the mud, and we crept ashore one at a time through mud and sedge.

The creek was edged with a bank of rough, broken ground, grown with coarse grass and bramble, and as we peeped over this bank the ruined house stood before us—so near as to startle me by its proximity. It must have been a large house originally—if, indeed, it was ever completed. Now it stood roofless, dismantled, and windowless, and in many places whole rods of brickwork had fallen and now littered the ground about. The black gap of the front door stood plain to see, with a short flight of broken steps before it, and by the side of these a thick timber shore supported the front wall. It struck me then that the ruin was perhaps largely due to a failure of the marshy foundation.

The place seemed silent and empty. Hewitt's footsteps were now plain to hear, and presently he appeared, walking briskly as before. He could not see us, and did not look for us, but made directly for the broken steps. He mounted these, paused on the topmost, and struck a match. It seemed a rather large hall, and I caught a momentary glimpse of bare rafters and plasterless wall. Then the match went out and Hewitt stepped within.

Almost on the instant there came a loud jar, and a noise of falling bricks; and then, in the same instant of time I heard a terrific crash, and saw Hewitt leap out at the front door—leap out, as it seemed, from a cloud of dust and splinters.

I sprang to my feet, but Plummer pulled me down again. "Steady!" he said, "lie low! He isn't hurt. Wait and see before we show ourselves."

It seemed that the floor above had fallen on the spot where Hewitt had been standing. He had alighted from his leap on hands and knees, but now stood facing the house, revolver in hand, watching.

There was a moment's pause, a sound of movement from the upper part of the ruin, another quiet moment, and then a bang and a flash from high on the wall to the right. Hewitt sprang to shelter behind the heavy shore, and another shot followed him, scoring a white line across the thick timber.

Plummer was up, and Styles and I were after him.

"There he is!" cried Plummer, "up on the coping!" I pulled out my own pistol.

"Don't shoot!" cried Hewitt. "We'll take him alive!"

Far to the right, on the topmost coping of the front wall, I could see a crouching figure. I saw it rise to its knees, and once more raise an arm to take aim at Hewitt; and then, with a sudden cry, another human figure appeared from behind the coping and sprang upon the first. There was a moment of struggle, and then the rotten coping crumbled, and down, down, came bricks and men together.

I sickened. I can only explain my feeling by saying that never before had I seen anything that seemed so long in falling as those two men. And then with a horrid crash they struck the broken ground, and the pistol fired again with the shock.

We reached them in a dozen strides, and turned them over, limp, oozing, and lifeless. And then we saw that one was Mayes, and the other—Victor Peytral!

We kept no silence now, but Plummer blew his whistle loud and long, and I fired my revolver into the air, chamber after chamber. Styles started off at a run along the path towards the town lights, to fetch what aid he might.

But even then we had doubt if any aid would avail Mayes. He was the under man in the fall, and he had dropped across a little heap of bricks. He now lay unconscious, breathing heavily, with a terrible wound at the back of the head, and Hewitt foretold—and rightly—that when the doctor did come he would find a broken spine. Peytral, on the other hand, though unconscious, showed no sign of injury, and just before the doctor came sighed heavily and turned on his side.

First there came policemen, and then in a little time a hastily dressed surgeon, and after him an ambulance. Mayes was carried off to hospital, but with a good deal of rubbing and a little brandy, Peytral came round well enough to be helped over the Marshes to a cab.

The trap which had been laid for Hewitt was simple, but terribly effective. The floor above the hall—loose and broken everywhere—was supported on rafters, and the rafters were crossed underneath and supported at the centre by a stout beam. The rafters had been sawn through at both ends, and the rotten floor had been piled high with broken brick and stone to a weight of a ton or more. The end of a loose beam had been wedged obliquely under the end of the one timber now supporting the whole weight, so that a pull on the opposite end of this long lever would force away the bricks on which the beam rested and let the whole weight fall. It was the jar of the beam and the fall of the first few loose bricks that had so far warned Hewitt as to enable him to leap from under the floor almost as it fell.

Peytral's sudden appearance, when we had time to reflect on it, gave us a suspicion as to some at least of the espionage to which Hewitt had been subjected—a suspicion confirmed, later, by Peytral himself after his recovery from the shock of the fall. For fresh news of his enemy had re-awakened all his passion, and since he alone could not find him, he was willing enough to let Hewitt do the tracking down, if only he himself might clutch Mayes's throat in the end. This explained the "business" that had called him away after the Barbican stronghold had been captured; finding both Hewitt and Plummer somewhat uncommunicative, and himself somewhat "out of it," he had drawn off, and had followed Hewitt's every movement, confident that he would be led to his old enemy at last. What I had told him of the cypher message had led him to hunt out Channel Marsh in the afternoon, and to return at midnight. He, of course, regarded the message, as I did myself at the time, as a perfectly genuine instruction from Mayes to Sims, and he came to the rendezvous wholly in ignorance as to what Hewitt was doing, and with no better hope than that he might hear something that would lead him in the direction of Mayes. He had entered the marsh after dark from the upper end, and had lain concealed by the other channel till near midnight; then he had crept to the rear of the ruin and climbed to where an opening seemed to offer a good chance of hearing what might pass in the hall. He had heard Hewitt approach from the front, and the crash that followed. The rest we had seen.