The conversation between Okiu and Miss Corbin was too low voiced for Fuller to catch any of it; and in a few moments he also drew in his head.

"Well," said he, "here's a state of things. First we find tracks which might be hers, then we come upon the shoes which she might have worn when she made them, now we see her engaged in secret conversation with a man whom we know to be——"

But Ashton-Kirk with an impatient gesture stopped him.

"Indications are not proof," said he, as he went into the hall. "Don't forget that we ourselves have also made tracks round about the window below, our shoes are also more or less caked with earth, and we have both spoken to Okiu."

"Of course that's so," said Fuller, "but nevertheless the facts are peculiar." He followed the other along the hall and into a room at the front of the house. "But, for that matter, everything having to do with this case is peculiar. I never saw a trail so snarled and crossed and recrossed. First you get the idea of a Japanese. Then Warwick is plunged into the thing so deep that I fail to see how he's ever going to extricate himself. Thirdly, we have enough proof as to Drevenoff's complicity to put him behind the bars; and now the probabilities are that the girl is also concerned."

Ashton-Kirk moved slowly about the room; it was one evidently used by Dr. Morse as a sort of lounging place, for there were sofas and big chairs and many books. At one side near the front window was a narrow antique desk of polished wood; it was open, and its contents had been tumbled about by the police. Ashton-Kirk sat down before it, annoyed and frowning.

"After an Osborne and a deputy coroner have been over the ground, one could drive a herd of mules over it without causing any appreciable difference in its aspect," said he. "They are as heavy handed as draymen."

And while he proceeded with a careful inspection of the contents of the desks, Fuller continued in a complaining tone:

"I'd like to know what we are to make of the whole business. Is it a sort of general conspiracy against Dr. Morse? Are Warwick, Miss Corbin and Drevenoff in league with the Jap for some particular purpose?—are there factions in the matter—each working for its own advantage?—or is every individual laboring for him or herself, and against all the others?"

"Mostly correspondence of a private nature," said Ashton-Kirk, as he ran through the papers. "Contracts with publishers, notes as to lectures, and negotiations for the delivery of the same."

There were some bits of jewelry of no particular value, a few small books of accounts and various odds and ends.

After some further search he lifted the writing bed of the desk, which was also the lid, and was about to close it; something seemed to attract his attention and he paused.

"Were you ever handed a bulky book and were surprised to find it extremely light?" said he to Fuller. "That oddity of thickness combined with lightness applies also to this lid."

The tip of the long inquiring finger ran along the edge of the lid; the quick, observant glance followed close behind. Instantly Fuller caught the suggestion.

"That's so," said he, eagerly; "it may be hollow."

"On each side of the lock," said Ashton-Kirk, "there is an inlaid strip. Look closely and you will see slight marks at the ends of each where the point of a knife has been inserted from time to time."

As he spoke he brought his own knife into play. Out came one of the inlaid pieces, disclosing a shallow opening. But it was empty. However, the second one revealed a number of sheets of paper. With the aid of the knife blade he managed to work these out; then spreading them upon the desk the two men examined them with attention.

"Hello," said Fuller, "here is that thing which I said a while ago looked like a ground plan."

"And here are the variously colored versions of the same, just as Warwick described them," said the secret agent. "They are precisely alike, but some are in brown, others in black, still others are in red, while some again are in blue. And here are the ones done upon neutral paper, in white."

"Is it possible, do you think," questioned Fuller, "that anything was meant by the differing colors?"

"There is nothing to convince me that such is not the case," replied Ashton-Kirk. "Chance seldom rules in a matter of consequence."

"Could the change in color not be ascribed merely to the fact that the draughtsman used the one that came first to his hand?"

"It may be. But see here: The design which you say resembles a ground plan differs in color, but is always the same in shape. But here are the other drawings. First there are a number of the crowned woman, all of which are done in brown. Then here are several duplicates of one which I saw the first time we came here. It is a cross, and in each case the down stroke is red and the cross stroke blue. Here the selection of colors never varies, and that there was a reason for clinging to these particular colors seems pretty evident. And that there was an equally good reason for changing the colors in the first design seems to me reasonable."

"Yes, it would appear so," admitted Fuller, but doubtfully. Then another sheet caught his eye and pointing to it, he inquired: "But what is that?"

Ashton-Kirk was reaching for the drawing when the question was asked. The squares of paper were exactly the size of the others, but the design upon it was totally unlike, however, and was done in heavy black. It was a picture of a human heart, and transfixing it were a number of pointed weapons resembling stilettos.

"What a murderous-looking thing!" observed Fuller. "Much like a Black Hand design as illustrated in the evening papers."

Ashton-Kirk did not reply; he bent down over the drawing as though inspecting it closely; then there was a considerable pause in which he did not stir and Fuller, watching, noted the glaze of introspection in the singular eyes. However, this was not for long; he suddenly straightened up; the other designs slowly passed through his hands once more; then he arose, a smile upon his face.

"More than likely that is it," said he.

"Is—what?" asked Fuller.

But the other allowed the interrogation to go unheeded.

"Away somewhere in our memories," said he, "there are many little bits of information all ticketed and ready to the hand of the person who cares to reach back for them. Those people who go through life with their eyes open possess more of these items of recollection than those who refuse to look beyond the confines of their own affairs. But the impressionable person—the one who makes no conscious effort to retain the things that buzz like bees about him—and yet catches them all much like the record of a phonograph—has the greater resources to draw upon."

"I would not call you one who made no effort," said Fuller. "And things must need be more or less proven to make an impression upon you."

"I make my effort in the particular line along which my interest runs at the time," said Ashton-Kirk. "And it is true that the things which I then accept must be more or less solidly supported by facts. But a newspaper casually picked up, a novel read as a time-killer, a spoken word, the gesture of a stranger in the street, or the unstudied action of a child, may convey a something that will stay with us for life."

"And just now," said Fuller, curiously, "you came upon one of these little incidents, a sort of unattached thing, which throws some light upon these," and he pointed to the drawings upon the desk.

Ashton-Kirk nodded; placing the sheets of paper in his coat pocket he closed the desk.

"The police will have little use for these," he said. "Nevertheless, I suppose I had better call Osborne's attention to them."

He spent another half hour in the upper part of the house, but nothing of interest met his eye. Then they descended to the first floor; and as they did so, met Miss Corbin upon the stairs. As she saw them, a startled look came into her face.

"Good-morning," said Ashton-Kirk.

"I did not know that you were here," she said.

"There were a few trifles which I knew only daylight would show us," he returned. "We came more than an hour ago."

"I did not see you go up-stairs," she said; and to Fuller there was a sort of confused resentment in her voice.

"We took the liberty of using the back stairway, that being the nearest," explained the secret agent.

There was a pause. The slim, girlish figure blocked their way; the great dark eyes were fixed upon them observantly. "You were in my uncle's room?" she asked.

"Yes. We fancied that there might be something there of interest."

"Ah, no doubt," she replied; and again Fuller's attention was called to a peculiar something in her voice. However, she said nothing more; and then as they stood politely aside, she passed on up the stairs.

The telephone bell was ringing furiously as they reached the hall; Osborne hastened from somewhere in the rear to answer it.

There followed the usual one-sided and enigmatic telephone conversation; but this one was interspersed with high-pitched questions, amazed ejaculation and wondering adjectives upon the part of the headquarters man. At last he hung up and turned to Ashton-Kirk.

"Well, what do you think of that?" he cried.

"What is it?"

"That was the chief. He's just had a wire from New York. They got on Warwick's track an hour after hearing from us, and traced him to an up-town hotel."

"Ah! And have they taken him?"

"Two plain clothes men went in and a couple more stood outside. The clerk said yes, he was in his room. Was registered under the name of Gordon. They went up and knocked. No answer. Knocked again. Still no answer. They broke down the door, and found——"

"What?" asked Fuller.

"That Warwick was gone. On the floor lay a traveling bag like the one he took from here, slashed open and empty, and beside it lay an unknown Japanese—stabbed through the heart."