The old man touched his hat, looked sharply towards Hewitt, who was waiting near the rectory door, and then disappeared round a corner of the house, the rector following. In a few seconds Mr. Potswood reappeared, with a slip of paper in his hand. "Here," he said, "see this! The old man was told to give it to n.o.body but me, and in n.o.body else's presence. He's been waiting since one o'clock."

Scrawled on the paper, in trembling and straggling letters, were these words:-

"You must not bring Mr. Martin Hewitt to my house this afternoon. I am watched. It is hopeless. Do not desert me. Bring him to-night after dark at eight. I shall want his best skill, and you shall know all. After dark. Come to the back gate in the lane, which will be ajar, and through the conservatory at the side, where my niece will be waiting at eight, after dark. Burn this and do not let it out of your sight first. Send a line by this man to say you will do as I ask, but do not say what it is, for fear of accidents. Send at once. Do come at eight, with Mr. Hewitt."

"We must do as he says," remarked Hewitt. "We know nothing of this matter, and we must be guided till we do. Just write an unsigned note-'All shall be as you request,' or words to that effect, and be sure the man gives it to him. Let him out behind through the churchyard, if possible, and tell him not to go straight from one house to the other. Is he an intelligent man?"

"Yes-uncommonly shrewd, I believe. He says he can't have been followed. He knows several gardeners hereabout, and he seems to have called on each of them on his way-in at the front of the garden and out at the back each time, after a few minutes' conversation. Gipps is rather a cunning old fellow."

"Ah," said Hewitt admiringly, "that's the sort of messenger I often want. I'll give him half a crown for himself and the money to pay for a telegram on his way. He knows nothing essential, of course?"

"No-only that his master is in some sort of trouble, and warned him that he might be followed."

"That is good. I shall telegraph to Detective-Inspector Plummer, of Scotland Yard. All right-I quite understand that all I have heard is confidential. I shall tell Plummer nothing till I may-indeed, as yet I have very little to tell that would help him. But I think it will be well to have the police within call-we may want them at a moment's notice; I have no police powers, you see, and Plummer has the Denson case in hand. I will ask him to be here, at this house, before a quarter to eight, if you will allow me."

And so the telegram went to Plummer, and Hewitt, accepting the rector's invitation to an early dinner before starting on their visit, resigned himself to wait. He did not like the waste of time, as he frankly told Mr. Potswood. He would have preferred to see Mason at once, at any risk, and to take what means he thought necessary without delay. But as it seemed that the risk was to be chiefly Mason's, and as Mason knew all of which both he and the rector were ignorant, Mason must be allowed to choose his own time.

The excellent Mr. Potswood endured agonies of suspense, though he also insisted that Mason's wishes must be observed exactly. "What is it all-what can it be?" he e.j.a.c.u.l.a.t.ed again and again. "What dreadful influence can thus compa.s.s a man about, here in London, in these times?"

It was autumn, and night fell early. Dinner was over at last, and they had scarcely left the table when Plummer arrived, anxious and eager.

"You'll have to trust me a little, Plummer," Hewitt said, when he had made him known to the rector. "I can tell you nothing now-know nothing, in fact, or very little more than nothing. The fact is, I'm going to see a man who promises information to me alone, in confidence, as his client, and I don't know how long I may have to keep you in the dark. But this is where the trail lies hot, and I know that's where you want to be. More, if you're wanted suddenly you'll be at hand. You have a man or two with you, I suppose, as I suggested?"

"Three of the best of them. They will follow us up. Is it far?"

"No, close enough. It is a house in a walled garden-not a high wall. We go in at a gate from the lane behind, and I think you should wait at that gate, and put your men at hand. We mustn't go in as a crowd. The rector had better go first, and you and I will follow on the opposite side of the road."

So the procession was formed, and it was still some three minutes short of eight o'clock when Hewitt and Plummer joined the clergyman at the door in the garden wall behind Mason's house. The door was ajar as had been promised in Mason's note. Leaving Plummer on guard without, Martin Hewitt and the rector stepped as silently as possible through the little kitchen garden and across a strip of lawn toward where a dull light illuminated the conservatory, at the right-hand end of the house. The door of the conservatory was ajar also, and this the rector pushed open.

"Miss Creswick!" the rector called, in a loud whisper. "Miss Creswick!" And with that a girl appeared within.

"Oh, Mr. Potswood," she said, "I'm so glad you've come! I can't think what's wrong with poor uncle! I'm afraid he must be going mad! He is terrified at something, and he has been getting worse, till he could hardly speak or walk. Dr. Lawson has been-about an hour ago, and since then uncle has been much quieter, in his study."

They were entering the dimly-lighted drawing-room now. "Dr. Lawson?" queried the rector. "Rather an unusual visitor, isn't he? How long has he been gone?"

Miss Creswick flushed slightly through all her paleness and grief. "I don't know," she said. "He let himself out, I fancy. He said he could not stay long when he came, but I didn't hear him go; I have been upstairs, and the servants are in the kitchen-they say uncle's mad, and I'm really afraid he is!"

They left the drawing-room, and walked along the corridor and the hall to the opposite side of the house, where the study lay. Miss Creswick tapped gently at the door, but there was no answer. She tapped again, louder, and then came the faint sound of a quick step on the carpet, and then a slight sc.r.a.ping noise, as when a door is closed over a carpet it will scarcely pa.s.s. "That's the window into the garden," said Miss Creswick. "Why is he going out? Uncle! Uncle Jacob!"

But now the silence was wholly unbroken. Hewitt s.n.a.t.c.hed quickly at the door-handle. "Locked!" he said. "Come-the quickest way into the garden!"

They ran out at the front door, and round toward the study window. It was a French window, exactly at the opposite end of the house to the conservatory, and now the gas-light streamed out through one half of it, which stood curtainless and ajar, while the curtain was drawn across the other half. Hewitt was the least familiar with the place, but he was quickest on his legs, and more seriously alarmed than the others. He reached the window first-and instantly turned and thrust the rector back against Miss Creswick. "Quick! take her away," he said; "we are too late!" and in the same moment, even as Hewitt dashed over the threshold, he s.n.a.t.c.hed a whistle from his pocket, and blew his hardest.

There on the floor lay Mason, his face dreadful and staring and black; tight in his neck was the band of a tourniquet, and fresh and wet on his forehead was the Red Triangle.

Hewitt s.n.a.t.c.hed at the screw of the tourniquet behind the neck, and loosened it as quickly as hands could turn. But it was too late. Too late, the examining surgeon afterwards said, by a quarter of an hour.

Plummer was at the window with his men at his heels even before the tourniquet was half unscrewed.

"Round the wall of the garden," shouted Hewitt, "and whistle up the police! He's only this moment out!"

The house was alive with shouts and screams. The rector came running back, and Hewitt, busy with his useless attempt at restoration, called now for a doctor. People were scampering in the street, and Hewitt left the victim to the care of the rector, and himself joined Plummer, all in fewer seconds than it may be told in.

But Plummer and his men were beaten, for nothing-not so much as a moving shadow-was seen in the garden or about the walls. Worse, the general trampling would obliterate possible tracks. Plummer set a guard of police about the wall, and came in for consultation with Hewitt.

The body was carried into another room, and Hewitt and Plummer began an examination of the study.

"No signs of a struggle," commented Plummer, "and there was no noise, they say. That's very odd."

"From what I have seen and heard to-day," said Hewitt, "it is as I should have expected. I believe the man was almost killed by terror before he was strangled-dazed, stricken dumb, paralysed, deafened by it-everything but blinded, poor wretch. And to have been blinded would have been a mercy."

And then, as they made their examination systematically, calmly and without flurry, Hewitt told the whole tale of his day's adventures, together with all he had heard from the rector. "The man's dead," he said, "and his confidence is at an end. Indeed, I never had it-the case, so far as I am concerned, is over before I have even touched it. I haven't had a chance, Plummer; and the thing is deep and dark, deep and dark. Oh, if only the man had let me come to him in the daylight, spite of all! This might all have been averted.... There has been a close search here, too. See how everything is turned over. But, stay!"

A low fire smouldered in the grate, and on it lay ashes of many burnt papers. Hewitt pa.s.sed the shovel carefully under these ashes, lifted them out and placed them gently on the table under the light of the gas-pendant.

"I must leave you," said Plummer. "There'll be an inspector here from the station in a moment-he won't interfere with you, and if anybody can get information out of this room it's you. The next thing for me is plain. I must make sure of Dr. Lawson, if he can be found."

"That is quite right, without a doubt," Hewitt responded. "I may find anything or nothing in this room, and, meanwhile, he was the last person known to have been here, and the only visitor, and he was not heard to go out, unless we heard him go when we were outside the study door. More, it was plainly some one familiar with the place who was able to get away so quickly by the window and the garden."

"And his interest in getting rid of Mason, too-the girl of age in a few months, and all obstacles to getting hold of her, and her money, removed. And-and the surgical tourniquet, the Chinese colour and everything!"

"Quite right, you must make sure of him, as you say. You will get his address from the rector. Meanwhile I'll try to begin my little contribution to the case-to begin it as best I can, after all the chances have made it useless."

III

It was after nine when Plummer returned. The rector had just rejoined Hewitt in the study, having left poor Miss Creswick, utterly broken down, in her room, in charge of a scarcely less terrified servant. Plummer tapped, and pushed the study door open.

"That's done clean and sure enough," he said, with professional calmness. "And he's a cool hand, is that Dr. Lawson. But have you found anything more? We shall want all we can get."

"We shall," Hewitt a.s.sented, "and we shall find more than we've got now, or I'm grievously mistaken. But tell me first what you've done."

He removed the blotting pad, on which the paper ashes still lay, and very carefully shut it away in a wide drawer where no draught could disturb it; he also shut another drawer which stood open.

"We had no difficulty in finding Dr. Lawson," Plummer began. "We met him, in fact, leaving his surgery. I went back with him into the gas-light, and there put it to him plump. Well, he was staggered, badly. Any man would be, of course. But he pulled himself together wonderfully soon, and the first thing he said was that he was just on his way to Mason's house. I thought at first, of course, that he meant to deny that he had been there already, and I gave him the usual warning about what he said being used in evidence. But he went on, and I've got it all safely noted. He admitted that he had been here, at about seven o'clock or just before, and he said he came because Mr. Mason sent for him. That doesn't seem likely, does it, on the facts as we know them?"

"Why, no," said the rector. "The last time he was here he was ordered out, and I know of no reason why he should have been asked to come to-day. We must ask if anybody was sent."

"I have asked," replied Plummer, "just now, and none of the servants was sent. But Lawson's story is that he was sent for and came, though he said he shouldn't say what Mason wanted to see him about till he knew more of the case. Looks as though he hadn't quite got his story ready yet, doesn't it? He had thought over the point about not being seen to go away, though; he said he had let himself out at about half-past seven, being familiar with the ways of the house. And he said that Mason was rather unwell-nervously upset-when he left him, but that was all."

"It's terrible," said the rector, "terrible. It seems impossible to believe it of young Lawson; and yet-and yet!" And then after a pause-"Good heavens!" he burst out again. "Why, I only realise it now! There is the other crime, too! Denson! Two murders! Two-and most certainly by the same hand! Mr. Plummer, I can't believe it! Oh, there's more behind, more behind, Mr. Hewitt."

"There is more," said Hewitt, "as you will see when I tell you the little I have been able to ascertain. There is more behind, though I see little of it yet. First--"

There was a sharp knock at the front door, followed by a ring, m.u.f.fled in the distant kitchen. Hewitt started up. "Who is this late visitor at this unvisited house?" he said. "If it is the police, well enough. But if anybody else-anybody-you may call me Doctor, or anything you please, except Martin Hewitt. Don't forget that!"

There were hurried steps in the hall, a question or two, and the study door was pushed open. Two servants-they would not venture from the kitchen singly this dreadful night-made a confused announcement of "Mr. Myatt," and were instantly pushed aside by Mr. Myatt himself, anxious and agitated.

The late Mr. Mason's closest scientific friend was a palish, black-bearded man, of above middle height, with stooping shoulders and a very quick pair of eyes. There was something about his face that somehow reminded Hewitt of portraits he had seen of John Knox, and yet it was not such a face as his; it seemed oddly unlike in its very likeness.