visibly.

"What's the matter?" demanded Erickson.

"Matter enough," was the amazing reply. "We've run into a den of some bandits. They must be the fiends who have been preying on the Earth-Mars shipping!"

The tremendous speed of the dive had brought them so close that all could see, without the aid of binoculars, the great skeletons of wrecked ships piled up at the base of the precipice.

"Tell those rats to go to hell," snapped Holden, "and get in touch with our own ships; use code and tell them to get here as quickly as possible, prepared for a fight. Get near enough to this pirate ship to open on it with the hexoxen guns. Can you keep them from ramming us, Edwards?"

"I think so, for a time, at least."

The enemy's craft was now only a few hundred yards away, and Holden scrutinized it closely for any sign that might give a clue to the original builders or present owners. Not over a hundred and fifty feet in length, with no visible openings, it looked like a slightly fattened steel needle. Its stern tubes were of the ordinary type; they glowed red against the silvery background, as the enemy swooped and circled, trying to get into position for a final, crushing blow.

"Every man in space suits," Holden ordered. "Good work, Linet," he cried, as he saw a sudden pock-mark appear in the pirate's side, where the devastating hexoxen bullet had struck.

"They've certainly got thick plates," remarked the Captain, as another direct hit failed to do more than scratch the metal. "Probably heavier up in front, if they mean what they say about ramming. I'm going to concentrate on the stern."

The dull red surface of the moon, the black walls of the crater, and the twinkling stars of outer space mingled in a fantastic whirl as Edwards skilfully kept the San Francisco out of the enemy's reach, at the same time giving Linet and the men in the observation compartment sufficient opportunity to train their guns on vital spots. It was a hopeless game, though, for the smaller ship was incredibly fast.

Erickson straightened up from his position behind the operator of the space-phone. "We can't make any connections with either the Ganymede or the Los Angeles. Probably these pirates have developed a shield which, thrown around their victims, prevents any message from getting to the outside."

That looked bad. Erickson switched the receiver back to the wave-length of the enemy. A continual stream of taunts and threats came from the loudspeaker.

"Why don't you surrender?" the gruff voice barked. "You haven't a chance against us, but if you surrender you may be allowed to work with us, for your own benefit as well as ours."

"Go to hell," the formerly meek Erickson roared into the transmitter, surprised at his own rage.

Then finally, with a desperate dash, the tiny pirate ship darted in. Edwards did his best to swerve away from the needle-point, but in vain. There was a shattering crash; Holden felt himself hurled through the air, but his heavy space-suit saved him from being crushed as he hit the wall of the room. Edwards stayed with the controls, somehow, cursing savagely.

"Only a glancing blow, but it smashed all the main stern tubes, and evidently disabled the anti-gravitational shield transmitter. We're going down."

Holden dashed to a port and glanced out. A welcome sight met his eyes. The enemy, also injured, was heading for home as fast as his disabled engines permitted.

"Those hexoxen bombs must have weakened his plating, so that it sprang when he rammed us," Edwards exclaimed when he saw what was happening.

Slowly the San Francisco sank toward the red and black volcanic ash of the crater floor. A hasty inspection revealed that Edwards had been correct in his diagnosis of the trouble. Extensive repairs would be necessary before they could proceed, but, fortunately, no one was seriously hurt, and the main shell showed no signs of strains or leaks.

As soon as Edwards had brought them safely to rest on the ground, Holden called a council of war.

"From the way these chaps fight, it's evident that they have no weapons, other than the bow of their ship, and possibly some short-range ray pistols, or the still more antiquated guns using some form of explosive to expel metal bullets. As soon as the shadow of the cliff throws this section of the crater into darkness, I'm going to do a little exploring, and see if I can't find out where these rats hide, when they're not out in space. Linet, you throw a line of pickets around the ship; Edwards, get started on repairs, and Erickson, keep on trying to get in touch with our companions."

Scarcely had he finished speaking when the light began to fade, and in a few minutes it was pitch black. Refusing to take anyone along with him, Holden crept out of the air-lock, and with an occasional glance at the compass fastened inside his suit, always pointing toward the San Francisco, he set out in the general direction of the wrecked space ships he had seen piled along the base of the cliff. He made good time, despite the weight of his suit and the poor footing afforded by the loosely piled dust, and finally saw ahead of him the silvery gleam of a ship's side. Afraid to use his light, he crept toward the bow of the craft, past a huge hole, and reached the name-plate. Following the deeply engraved characters, he slowly spelled out the name "G-L-O-R-," his heart gave a great thump. Gloriana, the Earth-Mars passenger transport into which his own Jean had stepped so happily a year previously!

A sudden hope flared up and then died down as he remembered the gaping hole he had just passed. The cowards had probably attacked without warning; the terrible cold of outer space had flooded through the opening made by that sharp-pointed prow,—. He could not bear to carry the image further; with a sob in his throat and murderous hatred in his heart, he continued his search for the pirate stronghold.

Winding his way among other shattered ships, he came to the base of the towering cliff, and turned to the right along it, finding his way by constantly touching the hard rock with his gloved hand. Suddenly there was a space where he could touch nothing, then the texture of the material changed.

Carefully shielding the glow, he flashed a light on the wall for a moment. It was metal, not rock! The pirates had walled in a cave with plates from the captured transports; probably they were living within, in all the luxury of their stolen wealth.

A few yards farther on his searching hand touched a seam in the metal, still farther, another, evidently the air-lock through which the pirates took their ship into the cave. Holden sat down to think. At that moment the wall against which he leaned began to move slowly outward! A dim ray of light came from the opening, which, as he turned to look, he saw to be an air-lock. The inner door was closed, obviously someone was expected to enter. He drew a deep breath, clasped his gun firmly in his right hand, and plunged in.

As soon as he entered, the outer door closed; he heard valves click open, air rushed into the chamber, and the inner door slowly opened, revealing a long hall, dark and ominous.

Without removing the helmet of his space-suit, he started down the hall, but had gone no more than a few steps before he felt a hand on his sleeve, drawing him through a darkened doorway. The door closed, a light flashed on, and before him stood, smiling and happy, his sweetheart, Jean!

With a single movement he flung off his helmet and seized her in his arms. For a short, delicious moment she clung to him, whispering those words that lovers know so well. At last she said, "We haven't a minute to lose, Jack. Let me tell you all I know about this place."

"But Jean, how did you get here? How does it happen that you had access to the air-lock?"

"I was captured by these fiends, and am a prisoner, together with about fifteen others,