For a moment, obtusely, I did not understand.

"She has made a secret appointment with him," she cried.

At last I saw the truth. Paula Lowe had fallen in love with the man she had sworn to kill!

CHAPTER II

THE ELECTRO-MAGNETIC GUN

"What shall we do?" demanded Burke, instantly taking in the dangerous situation that the Baron's sudden change of plans had opened up.

"Call O'Connor," I suggested, thinking of the police bureau of missing persons, and reaching for the telephone.

"No, no!" almost shouted Craig, seizing my arm. "The police will inevitably spoil it all. No, we must play a lone hand in this if we are to work it out. How was Fortescue discovered, Burke?"

"Sitting in a chair in his laboratory. He must have been there all night. There wasn't a mark on him, not a sign of violence, yet his face was terribly drawn as though he were gasping for breath or his heart had suddenly failed him. So far, I believe, the coroner has no clue and isn't advertising the case."

"Take me there, then," decided Craig quickly. "Walter, I must trust Miss Lowe to you on the journey. We must all go. That must be our starting point, if we are to run this thing down."

I caught his significant look to me and interpreted it to mean that he wanted me to watch Miss Lowe especially. I gathered that taking her was in the nature of a third degree and as a result he expected to derive some information from her. Her face was pale and drawn as we four piled into a taxicab for a quick run downtown to the laboratory of Fortescue from which Burke had come directly to us with his story.

"What do you know of these anarchists?" asked Kennedy of Burke as we sped along. "Why do you suspect them?"

It was evident that he was discussing the case so that Paula could overhear, for a purpose.

"Why, we received a tip from abroad--I won't say where," replied Burke guardedly, taking his cue. "They call themselves the 'Group,' I believe, which is a common enough term among anarchists. It seems they are composed of terrorists of all nations."

"The leader?" inquired Kennedy, leading him on.

"There is one, I believe, a little florid, stout German. I think he is a paranoiac who believes there has fallen on himself a divine mission to end all warfare. Quite likely he is one of those who have fled to America to avoid military service. Perhaps, why certainly, you must know him--Annenberg, an instructor in economics now at the University?"

Craig nodded and raised his eyebrows in mild surprise. We had indeed heard of Annenberg and some of his radical theories which had sometimes quite alarmed the conservative faculty. I felt that this was getting pretty close home to us now.

"How about Mrs. Annenberg?" Craig asked, recalling the clever young wife of the middle-aged professor.

At the mere mention of the name, I felt a sort of start in Miss Lowe, who was seated next to me in the taxicab. She had quickly recovered herself, but not before I saw that Kennedy's plan of breaking down the last barrier of her reserve was working.

"She is one of them, too," Burke nodded. "I have had my men out shadowing them and their friends. They tell me that the Annenbergs hold salons--I suppose you would call them that--attended by numbers of men and women of high social and intellectual position who dabble in radicalism and all sorts of things."

"Who are the other leaders?" asked Craig. "Have you any idea?"

"Some idea," returned Burke. "There seems to be a Frenchman, a tall, wiry man of forty-five or fifty with a black mustache which once had a military twist. There are a couple of Englishmen. Then there are five or six Americans who seem to be active. One, I believe, is a young woman."

Kennedy checked him with a covert glance, but did not betray by a movement of a muscle to Miss Lowe that either Burke or himself suspected her of being the young woman in question.

"There are three Russians," continued Burke, "all of whom have escaped from Siberia. Then there is at least one Austrian, a Spaniard from the Ferrer school, and Toma.s.so and Enrico, two Italians, rather heavily built, swarthy, bearded. They look the part. Of course there are others. But these in the main, I think, compose what might be called 'the inner circle' of the 'Group.'"

It was indeed an alarming, terrifying revelation, as we began to realize that Miss Lowe had undoubtedly been telling the truth. Not alone was there this American group, evidently, but all over Europe the lines of the conspiracy had apparently spread. It was not a casual gathering of ordinary malcontents. It went deeper than that. It included many who in their disgust at war secretly were not unwilling to wink at violence to end the curse. I could not but reflect on the dangerous ground on which most of them were treading, shaking the basis of all civilization in order to cut out one modern excrescence.

The big fact to us, just at present, was that this group had made America its headquarters, that plans had been studiously matured and even reduced to writing, if Paula were to be believed. Everything had been carefully staged for a great simultaneous blow or series of blows that would rouse the whole world.

As I watched I could not escape observing that Miss Lowe followed Burke furtively now, as though he had some uncanny power.

Fortescue's laboratory was in an old building on a side street several blocks from the main thoroughfares of Manhattan. He had evidently chosen it, partly because of its very inaccessibility in order to secure the quiet necessary for his work.

"If he had any visitors last night," commented Kennedy when our cab at last pulled up before the place, "they might have come and gone unnoticed."

We entered. Nothing had been disturbed in the laboratory by the coroner and Kennedy was able to gain a complete idea of the case rapidly, almost as well as if we had been called in immediately.

Fortescue's body, it seemed, had been discovered sprawled out in a big armchair, as Burke had said, by one of his a.s.sistants only a few hours before when he had come to the laboratory in the morning to open it.

Evidently he had been there undisturbed all night, keeping a gruesome vigil over his looted treasure house.

As we gleaned the meager facts, it became more evident that whoever had perpetrated the crime must have had the diabolical cunning to do it in some ordinary way that aroused no suspicion on the part of the victim, for there was no sign of any violence anywhere.

As we entered the laboratory, I noted an involuntary shudder on the part of Paula Lowe, but, as far as I knew, it was no more than might have been felt by anyone under the circ.u.mstances.

Fortescue's body had been removed from the chair in which it had been found and lay on a couch at the other end of the room, covered merely by a sheet. Otherwise, everything, even the armchair, was undisturbed.

Kennedy pulled back a corner of the sheet, disclosing the face, contorted and of a peculiar, purplish hue from the congested blood vessels. He bent over and I did so, too. There was an unmistakable odor of tobacco on him. A moment Kennedy studied the face before us, then slowly replaced the sheet.

Miss Lowe had paused just inside the door and seemed resolutely bound not to look at anything. Kennedy meanwhile had begun a most minute search of the table and floor of the laboratory near the spot where the armchair had been sitting.

In my effort to glean what I could from her actions and expressions I did not notice that Craig had dropped to his knees and was peering into the shadow under the laboratory table. When at last he rose and straightened himself up, however, I saw that he was holding in the palm of his hand a half-smoked, gold-tipped cigarette, which had evidently fallen on the floor beneath the table where it had burned itself out, leaving a blackened mark on the wood.

An instant afterward he picked out from the pile of articles found in Fortescue's pockets and lying on another table a silver cigarette case.

He snapped it open. Fortescue's cigarettes, of which there were perhaps a half dozen in the case, were cork-tipped.

Some one had evidently visited the inventor the night before, had apparently offered him a cigarette, for there were any number of the cork-tipped stubs lying about. Who was it? I caught Paula looking with fascinated gaze at the gold-tipped stub, as Kennedy carefully folded it up in a piece of paper and deposited it in his pocket. Did she know something about the case, I wondered?

Without a word, Kennedy seemed to take in the scant furniture of the laboratory at a glance and a quick step or two brought him before a steel filing cabinet. One drawer, which had not been closed as tightly as the rest, projected a bit. On its face was a little typewritten card bearing the inscription: "E-M GUN."

He pulled the drawer open and glanced over the data in it.

"Just what is an electro-magnetic gun?" I asked, interpreting the initials on the drawer.

"Well," he explained as he turned over the notes and sketches, "the primary principle involved in the construction of such a gun consists in impelling the projectile by the magnetic action of a solenoid, the sectional coils or helices of which are supplied with current through devices actuated by the projectile itself. In other words, the sections of helices of the solenoid produce an accelerated motion of the projectile by acting successively on it, after a principle involved in the construction of electro-magnetic rock drills and dispatch tubes.

"All projectiles used in this gun of Fortescue's evidently must have magnetic properties and projectiles of iron or containing large portions of iron are necessary. You see, many coils are wound around the barrel of the gun. As the projectile starts it does so under the attraction of those coils ahead which the current makes temporary magnets. It automatically cuts off the current from those coils that it pa.s.ses, allowing those further on only to attract it, and preventing those behind from pulling it back."

He paused to study the sc.r.a.ps of plans. "Fortescue had evidently also worked out a way of changing the poles of the coils as the projectile pa.s.sed, causing them then to repel the projectile, which must have added to its velocity. He seems to have overcome the practical difficulty that in order to obtain service velocities with service projectiles an enormous number of windings and a tremendously long barrel are necessary as well as an abnormally heavy current beyond the safe carrying capacity of the solenoid which would raise the temperature to a point that would destroy the coils."

He continued turning over the prints and notes in the drawer. When he finished, he looked up at us with an expression that indicated that he had merely satisfied himself of something he had already suspected.

"You were right, Burke," he said. "The final plans are gone."