One of the newest and fleetest of the Law Enforcement Vessels of the Triplanetary League, the heavy cruiser Chicago, of the North American Division of the Tellurian Contingent, plunged stolidly through interplanetary vacuum. For five long weeks she had patrolled her allotted volume of space. In another week she would report back to the city whose name she bore, where her space-weary crew, worn by their long "trick" in the awesomely oppressive depths of the limitless void, would enjoy to the full their fortnight of refreshing planetary leave.

She was performing certain routine tasks--charting meteorites, watching for derelicts and other obstructions to navigation, checking in constantly with all scheduled space-ships in case of need, and so on--but primarily she was a warship. She was a mighty engine of destruction, hunting for the unauthorized vessels of whatever power or planet it was, that had not only defied the Triplanetary League, but were evidently attempting to overthrow it; attempting to plunge the Three Planets back into the ghastly sink of bloodshed and destruction from which they had so recently emerged. Every space-ship within range of her powerful detectors was represented by two brilliant, slowly moving points of light; one upon a great micrometer screen, the other in the "tank"--the immense, three-dimensional, minutely cubed model of the entire Solar System.

A brilliantly intense red light flared upon a panel and a bell clanged brazenly the furious signals of the sector alarm. Simultaneously a speaker roared forth its message of a ship in dire peril.

"Sector alarm! N. A. T. Hyperion gassed with Vee-Two. Nothing detectable in space, but...."

The half-uttered message was drowned out in a crackling roar of meaningless noise, the orderly signals of the bell became a hideous clamor, and the two points of light which had marked the location of the liner disappeared in widely spreading flashes of the same high-powered interference. Observers, navigators, and control officers were alike dumfounded. Even the captain, in the shell-proof, shock-proof, and doubly ray-proof retreat of his conning compartment, was equally at a loss. No ship or thing could possibly be close enough to be sending out interfering waves of such tremendous power--yet there they were!

"Maximum acceleration, straight for the point where the Hyperion was when her tracers went out," the captain ordered, and through the fringe of that widespread interference he drove a solid beam, reporting concisely to G. H. Q. Almost instantly the emergency call-out came roaring in--every vessel of the Sector, of whatever class or tonnage, was to concentrate upon the point in space where the ill-fated liner had last been known to be.

Hour after hour the great globe drove on at maximum acceleration, captain and every control officer alert and at high tension. But in the Quartermaster's Department, deep down below the generator rooms, no thought was given to such minor matters as the disappearance of a Hyperion. The inventory did not balance, and two Q. M. privates were trying, profanely, and without much success, to find the discrepancy.

"Charged cells for model DF Lewistons, none requisitioned, on hand eighteen thous...." The droning voice broke off short in the middle of a word and the private stood rigid, in the act of reaching for another slip, every faculty concentrated upon something, imperceptible to his companion.

"Come on, Cleve--snap it up!" the second commanded, but was silenced by a vicious wave of the listener's hand.

"What!" the rigid one exclaimed. "Reveal ourselves! Why, it's ... Oh, all right.... Oh, that's it.... Uh-huh.... I see.... Yes, I've got it solid. Maybe I'll see you again some time. If not, so long!"

The inventory sheets fell unheeded from his hand, and his fellow private stared after him in amazement as he strode over to the desk of the officer in charge. That officer also stared as the hitherto easy-going and gold-bricking Cleve saluted briskly, showed him something flat in the palm of his left hand, and spoke.

"I've just got some of the funniest orders ever put out, Lieutenant"--his voice was low and intense--"but they came from 'way, 'way up. I'm to join the brass hats in the Center. You'll know about it directly, I imagine. Cover me up as much as you can, will you?" And he was gone.

Unchallenged he made his way to the control room, and his curt "urgent report for the Captain" admitted him there without question. But when he approached the sacred precincts of the Captain's own and inviolate room, he was stopped in no uncertain fashion by no less a personage than the Officer of the Day.

" ... and report yourself under arrest immediately!" the O. D. concluded his brief but pointed speech.

"You were right in stopping me, of course," the intruder conceded, unmoved. "I wanted to get in there without giving everything away, if possible, but it seems that I can't. Well, I've been ordered by Virgil Samms to report to the Captain, at once. See this? Touch it!" He held out a flat, insulated disk, cover thrown back to reveal a tiny golden meteor, at the sight of which the officer's truculent manner altered markedly.

"I've heard of them, of course, but I never saw one before," and the officer touched the shining symbol lightly with his finger, jerking backward involuntarily as there shot through his whole body a thrilling surge of power, shouting into his very bones an unpronounceable syllable--the password of the Secret Service. "Genuine or not, it gets you to the Captain. He'll know, and if it's a fake you'll be breathing space in five minutes."

Projector at the ready, the Officer of the Day followed Cleve into the Holy of Holies. There the grizzled four-striper touched the golden meteor lightly, then drove his piercing gaze deep into the unflinching eyes of the younger man. But that captain had won his high rank neither by accident nor by "pull"--he understood at once.

"It must be an emergency," he growled, half-audibly, still staring at his lowly Q. M. clerk, "to make Samms uncover his whole organization." He turned and curtly dismissed the wondering O. D. Then: "All right! Out with it!"

"Serious enough so that every one of us afloat has just received orders to reveal himself to his commanding officer and to anyone else, if necessary to reach that officer at once--orders never before issued. The enemy have been located. They have built a base, and have ships better than our best. Base and ships cannot be seen nor detected by any ether wave. However, the Service has been experimenting for years with a new type of communicator beam; and, while pretty crude yet, it was given to us when the Dione went out without leaving a trace. One of our men was in the Hyperion, managed to stay alive, and has been sending data. I am instructed to attach my new phone set to one of the universal plates in your conning room, and to see what I can find."

"Go to it!" The captain waved his hand and the operative bent to his task.

"Commanders of all vessels of the Fleet!" The Headquarters speaker, receiver sealed upon the wave-length of the Admiral of the Fleet, broke the long silence. "All vessels, in sectors L to R, inclusive, will interlock location signals. Some of you have received, or will receive shortly, certain communications from sources which need not be mentioned. Those commanders will at once send out red K4 screens. Vessels so marked will act as temporary flagships. Unmarked vessels will proceed at maximum to the nearest flagship, grouping about it in regulation squadron cone in order of arrival. Squadrons most distant from objective point designated by flagship observers will proceed toward it at maximum; squadrons nearest it will decelerate or reverse velocity--that point must not be approached until full Fleet formation has been accomplished. Heavy and Light Cruisers of all other sectors inside the orbit of Mars ..." the orders went on, directing the mobilization of the stupendous forces of the League, so that they would be in readiness in the highly improbable event of the failure of the massed power of seven sectors to reduce the pirate base.

In those seven sectors perhaps a dozen vessels threw out enormous spherical screens of intense red light, and as they did so their tracer points upon all the interlocked lookout plates also became ringed about with red. Toward those crimson markers the pilots of the unmarked vessels directed their courses at their utmost power; and while the white lights upon the lookout plates moved slowly toward and clustered about the red ones--the ultra-instruments of the Secret Service operatives were probing into space, sweeping the neighborhood of the computed position of the pirate's stronghold.

But the object sought was so far away that the small spy-ray sets of the Secret Service men, intended as they were for close-range work, were unable to make contact with the invisible planetoid for which they were seeking. In the captain's sanctum of the Chicago, the operative studied his plate for only a minute or two, then shut off his power and fell into a brown study, from which he was rudely aroused.

"Aren't you even going to try to find them?" demanded the captain.

"No," Cleve returned shortly. "No use--not half enough power or control. I'm trying to think ... maybe ... say, Captain, will you please have the Chief Electrician and a couple of radio men come in here?"

They came, and for hours, while the other ultra-wave men searched the apparently empty ether with their ineffective beams, the three technical experts and the erstwhile Quartermaster's clerk labored upon a huge and complex ultra-wave projector--the three blindly and with doubtful questions; the one with sure knowledge at least of what he was trying to do. Finally the thing was done, the crude but efficient graduated circles were set, and the tubes glowed redly as their solidly massed output was driving into a tight beam of ultra-vibration. "There it is, sir," Cleve reported, after some ten minutes of delicate manipulation, and the vast structure of the miniature world flashed into being upon his plate. "You may notify the fleet--co-ordinates H 11.62, RA 124-31-16, and Dx about 173.2."

The report made and the assistants out of the room, the captain turned to the observer and saluted gravely.

"We have always known, sir, that the Service had men; but I had no idea that any one man could possibly do, on the spur of the moment, what you have just done--unless that man happened to be Lyman Cleveland."

"Oh, it doesn't ..." the observer began, but broke off, muttering unintelligibly at intervals; then swung the visiray beam toward the earth. Soon a face appeared upon the plate, the keen but careworn face of Virgil Samms!

"Hello, Lyman." His voice came clearly from the speaker, and the Captain gasped--his ultra-wave observer and sometime clerk was Lyman Cleveland himself, probably the greatest living expert in beam transmission! "I knew that you'd do something, if it could be done. How about it--can the others install similar sets on their ships? I'm betting that they can't."

"Probably not," Cleveland frowned in thought. "This is a patchwork affair, made of gunny-sacks and hay-wire. I'm holding it together by main strength and awkwardness, and even at that it's apt to go to pieces any minute."

"Can you rig it up for photography?"

"I think so. Just a minute--yes, I can. Why?"

"Because there's something going on out there that neither we nor the so-called pirates know anything about. The Admiralty seems to think that it's the Jovians again, but we don't see how it can be--if it is, they have developed a lot of stuff that none of our agents has even suspected," and he recounted briefly what Costigan had reported to him, concluding: "Then there was a burst of interference--on the ultra-band, mind you--and I've heard nothing from him since. Therefore I want you to stay out of the battle entirely. Stay as far away from it as you can and still get good pictures of everything that happens. I will see that orders are issued to the Chicago to that effect."

"But listen...."

"Those are orders!" snapped Samms. "It is of the utmost importance that we know every detail of what is going to happen. The answer is pictures. The only possibility of obtaining pictures is that machine you have just developed. If the fleet wins, nothing will be lost. If the fleet loses--and I am not half as confident of success as the Admiral is--the Chicago doesn't carry enough power to decide the issue, and we will have the pictures to study, which is all-important. Besides, we've probably lost Conway Costigan to-day, and we don't want to lose you, too."

Cleveland remained silent, pondering this startling news, but the grizzled Captain, veteran of the Fourth Jovian War that he was, was not convinced.

"We'll blow them out of space, Mr. Samms!" he declared.

"You just think you will, Captain. I have suggested, as forcibly as possible, that the general attack be withheld until after a thorough investigation is made, but the Admiralty will not listen. They see the advisability of withdrawing a camera ship, but that is as far as they will go."

"And that's plenty far enough!" growled the Chicago's commander, as the beam snapped off. "Mr. Cleveland, I don't like the idea of running away under fire, and I won't do it without direct orders from the Admiral."

"Of course you won't--that's why you are going...."

He was interrupted by a voice from the Headquarters speaker. The captain stepped up to the plate and, upon being recognized, he received the exact orders which had been requested by the Chief of the Secret Service--now not as secret as it had been heretofore.

Thus it was that the Chicago reversed her acceleration, cut off her red screen, and fell rapidly behind, while the vessels following her in their loose cone formation shot away toward another crimson-flaring leader. Farther and farther back she dropped, back to the limiting range of the ultra-cameras upon which Cleveland and his highly trained assistants were furiously and unremittingly at work. And during all this time the forces of the seven sectors had been concentrating. The pilot vessels, with their flaming red screens, each followed by a cone of space-ships, drew closer and closer together, approaching the Fearless--the British super-dreadnaught which was to be the flagship of the Fleet--the mightiest and heaviest space-ship which had yet lifted her stupendous mass into the ether.

Now, systematically and precisely, the great Cone of Battle was coming into being; a formation developed during the Jovian Wars while the forces of the Three Planets were fighting in space for their very civilizations' existence, and one never used since the last space-fleets of Jupiter's murderous hordes had been wiped out.

The mouth of that enormous hollow cone was a ring of scout patrols, the smallest and most agile vessels of the fleet. Behind them came a somewhat smaller ring of light cruisers, then rings of heavy cruisers and of light battleships, and finally of heavy battleships. At the apex of the cone, protected by all the other vessels of the formation and in best position to direct the battle, was the flagship. In this formation every vessel was free to use her every weapon, with a minimum of danger to her sister ships; and yet, when the gigantic main projectors were operated along the axis of the formation, from the entire vast circle of the cone's mouth there flamed a cylindrical field of force of such intolerable intensity that in it no conceivable substance could endure for a moment!

The artificial planet of metal was now close enough so that it was visible to the ultra-vision of the Secret Service men, so plainly visible that the warships of the pirates were seen issuing from the enormous air-locks. As each vessel shot out into space it sped straight for the approaching fleet without waiting to go into any formation--gray Roger believed his structures invisible to Triplanetary eyes, thought that the presence of the fleet was the result of mathematical calculations, and was convinced that his mighty vessels of the void would destroy even that vast fleet without themselves becoming known. He was wrong. The foremost globes were allowed actually to enter the mouth of that conical trap before an offensive move was made. Then the vice-admiral in command of the fleet touched a button, and simultaneously every generator in every Triplanetary vessel burst into furious activity. Instantly the hollow volume of the immense cone became a coruscating hell of resistless energy, an inferno which, with the velocity of light, extended itself into a far-reaching cylinder of rapacious destruction. Ether-waves they were, it is true, but vibrations driven with such fierce intensity that the screens of deflection surrounding the pirate vessels could not handle even a fraction of their awful power. Invisibility lost, their defensive screens flared briefly; but even the enormous force backing Roger's inventions, greater far than that of any single Triplanetary vessel, could not hold off the incredible violence of the massed attack of the hundreds of mighty vessels composing the Fleet. Their defensive screens flared briefly, then went down; their great spherical hulls first glowing red, then shining white, then in a brief moment exploding into flying masses of red hot, molten, and gaseous metal.

A full two-thirds of Roger's force was caught in that raging, incandescent beam; caught and obliterated: but the remainder did not retreat to the planetoid. Darting out around the edge of the cone at a stupendous acceleration, they attacked its flanks and the engagement became general. But now, since enough beams were kept upon each ship of the enemy so that invisibility could not be restored, each Triplanetary war vessel could attack with full efficiency. Magnesium flares and star-shells illuminated space for a thousand miles, and from every unit of both fleets was being hurled every item of solid, explosive, and vibratory destruction known to the highly scientific warfare of that age. Offensive beams, rods and daggers of frightful power struck and were neutralized by defensive screens equally capable; the long range and furious dodging made ordinary solid or high-explosive projectiles useless; and both sides were filling all space with such a volume of blanketing frequencies that such radio-dirigible torpedoes as were launched could not be controlled, but darted madly and erratically hither and thither, finally to be exploded harmlessly in mid-space by the touch of some fiercely insistent, probing beam of force.

Individually, however, the pirate vessels were far more powerful than those of the fleet, and that superiority soon began to make itself felt. The power of the smaller ships began to fail as their accumulators became discharged under the awful drain of the battle, and vessel after vessel of the Triplanetary fleet was hurled into nothingness by the concentrated blasts of the pirates' rays. But the Triplanetary forces had one great advantage. In furious haste the Secret Service men had been altering the controls of the radio-dirigible torpedoes, so that they would respond to ultra-wave control; and, few in number though they were, each was highly effective.

A hard-eyed observer, face almost against his plate and both hands and both feet manipulating controls, hurled the first torpedo. Propelling rockets viciously aflame, it twisted and looped around the incandescent rods of destruction so thickly and starkly outlined, under perfect control; unaffected by the hideous distortion of all ether-borne signals. Through a pirate screen it went, and under the terrific blast of its detonation one entire panel of the stricken battleship vanished, crumpled and broken. It should have been out, cold--but, to the amazement of the observers, it kept on fighting with scarcely lessened power! Three more of the frightful space-bombs had to be exploded in it--it had to be reduced to junk--before its terrible rays went out; Not a man in that great fleet had even an inkling of the truth; that those great vessels, those terrible engines of destruction, did not contain a single living creature: that they were manned and fought by automatons; robots controlled by keen-eyed, space-hardened veterans inside the planetoid so distant by means of tight, interference-proof communicator beams!

But they were to receive an inkling of it. As ship after ship of the pirate fleet was blown to pieces, Roger realized that his navy was beaten, and forthwith all his surviving vessels darted toward the apex of the cone, where the heaviest battleships were stationed. There each hurled itself upon a Triplanetary warship, crashing to its own destruction, but in that destruction insuring the loss of one of the heaviest vessels of the enemy. Thus passed the Fearless, and twenty of the finest space-ships of the fleet as well. But the ranking officer assumed command, the war-cone was re-formed, and, yawning maw to the fore, the great formation shot toward the pirate stronghold, now near at hand. It again launched its stupendous cylinder of annihilation, but even as the mighty defensive screens of the planetoid flared into incandescently furious defense, the battle was interrupted and pirates and Triplanetarians learned alike that they were not alone in the ether.

Space became suffused with a redly impenetrable opacity, and through that indescribable pall there came reaching huge arms of force incredible; writhing, coruscating beams of power which glowed a baleful, although almost imperceptible, red. A vessel of unheard-of armament and power, hailing from a distant solar system of the Galaxy, had come to rest in that space. For months her commander had been investigating sun after sun in quest of one precious substance. Now his detectors had found it; and, feeling neither fear of Triplanetarian weapons nor reluctance to sacrifice those thousands of Triplanetarian lives, he was about to take it!