"Tama can control them. Doc."

"I hope so. I've spoken to her. She stared at me with that little quizzical smile. 'Oh, yes. Doctor, we will be prudent.

We look to you to tell us what to do.' That sounds fine. But" Jimmy interrupted. "What I was saying; my idea is well have these savages penned in the mountains. You're not going to attack at once. Make the girls take it slow; that will help control 'em. It will be dark, won't it?"

"So I understand."

"Abnormally dark. Roc tells me this sky looks as though a black storm is coming. And a cold one, from the Night ' Country. Well, my idea is to watch my chanceget my platform up close to the enemy lines. Wear a black insulator ,_suit, and creep through the lines. Get up to the ballunseen, why not? And the doorway would probably be open"

"But, Jimmy, you can't walk with that leg."

"I can creep, can't I? I may have no chance after the fighting starts, to consult with you. I want your permission now. It might be the lives of Rowena and Jackand it might make all the difference between your losing or winning the battle. You want those barbarians coming to the Earth againassaulting, abducting young girls like they did last year? If I get Rowena and Jackyou'll be free to blow that ball to bits. Chances are that Dorrek and all the leaders will be in it.

Grenfell hesitated; then he put his hands on Jimmy's shoulders and gazed into the flushed, freckled face with the tousled, brick-red hair above it.

"Do what you think best, Jimmy. Onlydon't get killed." As Grenfell stood up, Jimmy saw Roc standing a short distance down the length of dimly illumined deck. He had come from a nearby door, or perhaps he had been standing there unobserved for some time. Jimmy called, "Oh, Roc come here." Roc was to be his companion on the platform. Jimmy was by nature impulsive, and he was keyed up, excited now.

He gave Roc the general idea of his plan.

"Suppose we try it together. Roc. You'll be a great help if we should be stopped by any of Dorrek's men, since you can talk their language." Roc said quietly, "We are riding together. Plenty of time to talk it over later, Turk." Roc turned to Grenfell. "Tama would like to see you for a moment, Dr. Grenfell. Some question about shields for the girls."

"Oh-yes, Roc." He and Roc hurried away, leaving Jimmy alone, nursing his leg, pondering his plan.

And he was still pondering it, when in the midst of the cloud of flying girls, he rode the platform with Rocthe metallic desert beneath them, and overhead the lowering black sky. A black storm was coming.

Roc was stretched now at the platform stem; Jimmy was fa front. At the handles, jutting out, their girls flew, seven on each side. Only one of them spoke English, and hers was very limited. A girl named Grazia. She flew at the lefthand leading position, her wing-stroke setting the beat for the others. Her small, earnest face, flushed with exertion, was only a few feet from Jimmy's. Occasionally, as she turned to glance at him, he would smile and nod to her, or call a chasing jovial encouragement. The girls of this crew all seemed to like Jimmy. But they obviously did not like Roc.

At last, far ahead against the dark horizon, the black peaks of the mountains loomed up.

Like a great gash in the tumbled mountainous ridge wound the black canyon. Its smooth metallic walls were for the most part sheerly perpendicular, a thousand feet high. It was narrow, frequently curving in broad sweeps, or again turning sharply. In places it was five hundred feet wide, in others less than two hundred.

The walls were eroded with lateral ridges, one above the other as though left by nature to mark the ages of the drying river which once had surged through here. In the heart of the Dark Mountains, the canyon widened abruptly into a great irregularly shaped bowl, where once a lake must have been. Nearly circular, it was some six miles in diameter: A broken, ridged floor of strewn boulders, gullies and ravines, surrounded by sheer circular walls like a crater rim, broken and jagged on top.

In this great bowl, Dorrek had set his encampment. His forces were arriving from the upper canyon entrance at the Cold Country side; and it was from the lower canyon entrance that Grenfell and his army approached. Grenfell learned afterward that Dorrek's force was already almost complete. What few came later, seeing the distant conflict, undoubtedly turned back and fled.

As Jimmy rode his swaying platform, winging low over the narrowing black canyon, he could see very little of the region's formation. It was now almost black night. The Cube had sailed ahead. Twenty girls had gone cautiously with the Cube. They came winging back, flying in broken formation, scattering to the flying platforms and to the leaders of the various crops of girls with Grenfell's orders.

Jimmy and Roc saw the alarm given long before their platform arrived upon the scene. Light flares bursting in the distance, illumed the black sky and the towering jagged mountain peaks. The steady, rumbling hiss of giant projectors.

Jimmy thought that the attack had already begun. The Cube came sailing back, high overhead, turned in a tenmile semicircle, and swept forward again.

One of the largest platforms carrying a huge projector with four men to operate it dropped down and landed upon the canyon rim at the entrance to the six-mile bowl. The canyon here was no more than two hundred feet wide. The projector, mounted upon the rim, would dominate this exit.

Half of Grenfell's force landed at this point. The other half, including Jimmy and Roc, swept a mile back to the left, avoiding the open bowl. Jimmy saw great shafts of blue-green light rays standing like searchlight beams into the air. A cir-ular curtain of deadly hght in the center of the bowl.

Jimmy and Roc, following orders, flew in a wide detour to the left and landed on the crater rim, where the canyon stretched off toward the Cold Country. There were a few of Dorrek's guards on the top of these walls, but at once they scattered and fled.

Dorrek was now trapped in the rocky bowl. As Grenfell had foreseen, he went instantly on the defensive. When the alarm came, the silver ball had been resting at the bottom of the valley near one of its side walls. Dorrek immediately moved it to the center of the bowl, three miles from the nearest enclosing cliffs.

Two hours passed, which were horribly irksome to the waiting Jimmy.

Near the top of the thousand-foot precipice at the opening to the valley, Grenfell's encampment was springing into existence on a boulder-strewn plateau. The Cube had landed on a nearby rocky eminence which dominated the scene.

The men and the four hundred girls unloaded the Cube's supply of tents, lights, cables, batteries and light mechanisms; the food supplies; weapons and defensive armament.

Within an hour the tents and lights were erecteda little huddled group of dark-fabric shelters, strewn amid the rocks.

Tiny hooded green lights dotted it, their dim radiance disclosing the figures of the winged girls moving busily about The first meal was in preparation.

Jimmy called to Roc as the Mercurian laboriously hauled the base section of a projector to a spot where someone had said it should be taken.

"How far is the brink from here? I'm going there." Roc answered his smile. "Of course, Turk." He called a passing' girl, instructed her to have the projector assembled.

very well, Turk. Come put your arm on my shoulder." Jimmy found that he could almost hobble. He weighed hardly sixty pounds here on Mercury. With his arm over Roc's shoulders, they made a fair speed, passing beyond the lights of the camp, heading to the nearby brink where they could see over the valley.

Fragments of information which Roc had picked up he now gave Jimmy. Dorrek was caught in the valley. His m."" and brues were dovm there clustered around the silver ba~ In all, they occupied a space of about a mile-wide circle, out in the center of the valley. There was no projector in either camp which could reach the other.