Grenfell had made sure that Mercury was his destination.

And as we fell into position over the planet, the Cube drew again into sight above us, following us down. And then we plunged into the cloud masses. The Cube was lost to our sight.

Descending the atmosphere, a rush of new problems came to the interior of our tiny falling world. Roc was tensely active, giving orders for the handling of the controls, which Dorrek and his men anxiously obeyed. Jimmy and I and the two girls were for a time ignored. We made plans for escape, and watching the activity around us.

This plunge from the cold of interplanetary space to the friction-heat of the atmosphere brought the temperature controls of the vehicle into constant operation. And with the swift-changing temperatures, for all Roc could do to keep them equalized, came pressure changes of our interior air.

This required skillful manipulation.

Dorrek and the others did Roc's bidding with an eager desire to make no errors. It was obvious that the safety of the ball depended now on Roc's skilland Dorrek had not dared cross him. Roc had told us so with his cynical smile.

But once into the lower atmosphere, with the door and windowports open. Roc would no longer be needed. Dorrek and his men could then safely fly the vehicle.

I whispered to Jimmy and to the girls, "Be careful, now! We'll land in an hour or somake the rush. Don't turn your back on anyone for a second)" We were in the largest room in the lower tier of the ball.

Most of the Mercurians were dispersed elsewhere at the various controls. Dorrek was in and out of the room, relaying his .orders. In a corner angle, Muta sat on a low setteea shapeless lump with her deformed wings spread out behind her. Her eyes clung to us with that expressionless, fathomless gaze.

I had my cylinder m a trouser pocket, and the revolver m the flap of my boot. Jimmy, in his tight-fitting trousers, puttees, and thin gray shirt, with sleeves rolled up and collar wide, sat dejectedly beside me and mopped his forehead in the heat.

"Hot, Jack! My heavens" I knew that he was tense, with his hidden cylinder ready for instant action. In outward aspect, to the gaze of Dorrek and Muta, we were docile prisoners.

We had found an opportunity of purloining a small knife for each of the girls. Even Roc did not know they had them.

For use if the worst should come. I prayed that it might not.

We burst presently through the clouds. The landscape of Mercury lay spread in the half-light of day beneath the ball.

We crowded to one of the window ovals, and in a moment Roc joined us. Dorrek, in command of the ball now, had momentarily left the room; but Muta did not move.

"I will open the door soon," Roc whispered. He gazed down through the window. "We are not far from the Water City." I glanced out, but at once turned back. "Roc, is that woman armed?"

"No, I do not think so. A knife, perhaps." I strode across the room.

"Muta!" She lifted her dark gaze. "What you want?"

"Roc says, go to another room." I gestured. "You go and make food for us. For mehungry" She did not move. It seemed that the shadow of a smile plucked at her heavy, shapeless mouth. Her eyes, like vacant dark pools, gazed at me. Then she looked away. But she did not move.

"Do you understand me, Muta?"

"Yes." Roc joined me and gave her a brusque command in Mercurian. She gazed at him suUenly.

Dorrek came in. I saw Roc hesitate. Then evidently he told Dorrek that she was to go. My breath stopped; my hand went to my hidden weapon. Across the room Jimmy took a tense forward step. It seemed in that breathless instant that the conflict we feared was upon us. I saw in the inner doorway three Mercurians crowding forward.

Then Roc laughed, waved at Dorrek and pulled me away.

Muta sat motionless. The giant Dorrek's gaze swept us all.

But he did not speak, and turning, he pushed his fellows back and left the room.

Roc whispered, "They will no longer obey me. You saw it?" We went back to the window.

"God, I thought it had startedl" Jimmy exclaimed.

To fire these ray cylinders here in these tiny rooms was doubtless as terrifying to Dorrek as to any of us.

"Open the door," Jimmy whispered. "Let's get out of this.

Order us to land." Roc nodded. "Our interior air pressure is a little low.

In a moment." Beneath my window I saw a great spread of naked landscapethe Light Country, fairest region of the planet! The daylight glistened on the naked surface of bleak, metallic hills. There had recently been a storm; the bumished hillsides were wet with moisture, and little rills and pools of water filled the rock depressions.

Desolate spread of landscape I No soil, no blade of vegetation. The convexity of this small world was obvious. An undulating metallic plain, and off to one side a range of naked little hills, with buttes, square-sided, flat-topped, and spires like pointed minarets rising against the flat monochrome background of the sky.

We fell lower, swept on at an altitude of not over fifteen hundred feet. Tama stood beside me. She gestured. "The Hill City is not far. And the Water City is ahead of us.

They have had a black storm not long ago. See the water on the rocks." We passed almost over a valley. Soil was there. Porouslooking trees, suggesting a mushroom growth, fringed a little lake. There were small areas with a red soil plowed up.

And set in a long strip at the bottom of one of the enclosing hillsides was a collection of little hutscrude habitations built* of the porous treetrunks, thatched with huge, dried leaves.

A deserted camp. There seemed a litter of equipment lying abandoned. Agricultural implements stood in the fields where a vegatation growth had come up, unharvested, and died again... . We passed on in a moment once more over the metallic desert.

"That was one of our girls' camps," Tama said. "Abandoned when we returned to the Hill City. You remember it, Roc? You ought toyou drove us there."

"The camp of the flying virgins. Guy had told us of those events. Only the women of Mercury were endowed vidth wings, and the men, by instinct, were jealous. Man-made laws decreed that at marriage the wings of a virgin should be clipped.

The revolt of the virgins, smoldering for years, had come at last. Led by Tama, they had pleaded for different laws.

Instead of which, led by the sly Roc, the government had passed a new, more drastic law. Even before marriage, at the age of sixteen, the virgins were ordered to accept the mutilation. They had revolted, flown from the Hill City, the Water City and elsewhere, and established this camp in the desert. And then when Roc had proved a traitor, stolen the government secrets of war and joined his outlawed father in the Cold Country, the Hill City government had been repentant. Alarmed at the lengths to which it had forced the young girls, it had begged them to come back, promising them new laws.

They had gone back, just before Tama and Guy had left for Earth. That was the situation, all we knew of it, save that here in the silver ball we had learned of the coming invasion of the Light Country by the Cold Country barbarians.

Whether the Hill City government was prepared for it or not we could not say. Our duty now was to get to the Hill City and warn them.

The welfare of our own Earth was at stake as well. The present Hill City government would never make a raid on Earth. But if the barbarians were victorious here on Mercury, raids upon Earth were inevitable.

Rowena touched me. "Look off there!" Against the distant sky little moving dots were visible: a group of flying girls winging off toward the Hill City. And down on the naked plateau, a few miles away, men were moving.

We came over the horizon to a new vista. Human figures moved on foot. Several groups at intervals, hastened laboriously forward. They were fairly distant, mere dots. But there seemed to be men, and women and children as well. A cart or two drawn by peculiar long creatures close to the ground.