It seemed like a flight, a routas though these were refugees, with belongings hastily gathered in the face of some disasterall heading toward the Hill City.

Then the horizon rim showed othersa line of tiny dots.

Then several distant group of girls, coming from the Hill City, circling over the figures on the ground, and winging back.

They had doubtless seen our vehicle, and fearing it, kept well away.

This had come upon us all in a few moments as our flyer sped forward. I saw that Tama was white and grim. She stood clutching at Rowena, whispered to her. Horror swept Rowena's face.

Jimmy whispered, "What in the devil, Jack" Roc had not been looking out of the window. He said abruptly, "Our pressure is right. I shall open the door." Dorrek was not here. Muta made no move. Roc unclamped the mechanism; the thick little panel slid aside. The air of Mercury surged in with a gust upon us: Moist, heavy air, with the smell of rain and a hint of sulphur in it from the recent storm.

The change of pressure appraised Dorrek that the door was open. He appeared at once and stood gazing at us.

The open doorway was near us allsix feet high, and half as widea threshold with a fifteen hundred drop down to the rocky plain beneath us.

Dorrek made no move. There came a cry from Tama.

"Roc-look! The Water Cityl" Ahead of us at the horizon a low-hanging murky cloud had appeared over a range of hills, with what I assumed was the Water City still hidden behind them. In a moment we could see clusters of figures on the distant hilltops.

A little blob of light rose in an arc, went over the line of hills and fell into the still hidden city. A rocket bomb! This was an attack! We all forgot Dorrek and Muta behind us.

Tama cried, "Roc, this is the invasionalready started! You have tricked ustricked me again!"

"No, Tama. I swear I had no idea of this!" He seemed speaking the truth. He swung around. "Look at Dorrek, Tama! If you think I lie, look at Dorrekl He is as surprised as I am." The giant had glimpsed the scene through the window near him. He called Muta. Momentarily ignoring us, they flung open the breast-high circular pane and stood gazing with obvious astonishment.

The sphere swept on, rising to a higher altitude to pass over the line of hills. Presently the stricken Water City lay beneath us.

Fantastic, ghastly scenes unrolled to our horrified gaze.

VIII WASTE THE LITTLE LINE of jagged hills had behind it a sheer drop of perpendicular copper walls, clean as though cloven by Titan's knife. Beyond them the contour was a wide-spreading, shallow oblong bowl, with gentle slopes undulating upward to other heights at the distant horizon.

A small inland sea had once been here. It was gone now but, at the bottom of the depression, water still collected, making a little lake some two miles wide, with the city houses built on stilts and water treesa spring-fed lake of turgid, warm water rising from the fire-heart of the planet.

The copper precipice stood against the lake; to the left it straggled into a marsh as the land rose up. There were fields on the terraced hillsides off there, spreading in a great semicircle beyond the laketerraces of water and mud in which something like rice might be growing. To the right the lake drained in a slow-moving, sluggish little river that wound off into the distance between canyon walls.

We stood gazing from the window of the silver ball at a height of some two thousand feet. Gray-black clouds were over us; the scene was flat and dim in the half light of day.

And the murk of gas fumes and smoke clung to the city, hiding it. A murk of horror! We passed along the peaks of the rim at the top of the.

precipice walls. The figures of men were massed down there.

A flare burst momentarily to illumine them. Men garbed in animalskins; men like Dorrek and his fellows of the Cold Country.

A giant projector sent dowra spurt of light-fire like a lightning bolt. It split the smoke cloud that hung on the city.

A rift, through which I saw a little group of thatched buildings perched like a cluster of birds' nests between the huge stems of water trees. A tiny segment of the city was made suddenly visible, with a tangle of water plants rising thirty or forty feet above the lake surface. The huts were woven into this junglelaced platforms, with oval mounds of thatch upon them. There were six or eight of them in this cluster, set upon different levels. Leaves like giant palm fronds hung around them, with interlacing vines, woven into ladders.

The heat-ray bolt hurled itself down. I saw the birds' nest houses wither, shrivel and fall to the water in a strewn little heap of wreckage. Human bodies were floating in it.

I saw a woman with broken wings trying to flap upward.

She struggled an instant and then fell back.

The bolt's duration was only a second or two, when the murk closed again. I turned to see Tama staring at Roc.

Her voice rang with horrified accusation: "That projector! You and your father stole the plans for those weapons!" He gripped her. "Yes, I did! I'm sorry, Tama." He ended with a wild laugh. "Lookthey do not know how to use it-" I looked down on the rocky hilltop, where the projector burst into a puff of light. The figures clustered about it were gone. There was only a small blackened patch of empty rock.

We moved on, out over the city. Roc was laughing wild~ "This attack! They should have waited for mel Or you, Dorrek!" He swung toward the giant. "You saw that? They are not readythey do not know how to use their weapons." Dorrek shouted an order to one of his fellows. Our vehicle swung slowly over the city, turning on its axis and making a great circular sweep. The scenes we saw down in the gloom were fragmentary. I recall them now as a kaleidoscope of horror.

Men dying on the precipice top, and men fighting off on the distant terra-ced slopes. An occasional rocket flare rose in a slow arc and burst in the city. Brief vistas of shriveling houses.

Presently the rockets and bombs ceased. Grayness fell upon the scene. Then a wind from the distant mountains sprang up. The murk began rolling aside. The city opened to our sight.

The attack was almost over. On the terraces the clusters of men, and those dark oblong things slithering on the ground, began moving away. In the distance I saw moving dots in the skygirls, who had flown up from the menaced city and escaped. And other patches, dark and leprousholes where the black water showed, strewn with shriveled litter.

As the smoke swept away, we descended. We turned at the entrance to the little canyon where the river wound into the naked hills, and swung back. I saw, in the strewn river surface, blackened, shriveled bodies floating off.

There was a little patch of open water like a city street with tree stems lining it and the houses still intact. Something was still living, swiming down there. An oblong thing. It reared its head, came to a half-fallen tree, began climbing the incline of the trunk. It had a jointed body some ten feet long and myriad short, spindly legs. A round head, with waving arm-like antennae. A "brue" one of the giant' insects! There were some larger than this one. Guy had told us of them, how they were domesticated in the Hill City.

I saw this one leave the water and slither up the treetrunk. It reached a house platform, against which the top of the fallen tree was resting. A woman was lying there on the platform. Her wings were burned away, her body mangled so that she seemed even unable to crawl. But she was still alive, lying against the thatched side wall of her home. At her breast a white-skinned, golden-haired little girl was huddled in the dying mother's arms. The child's paleblue wings were flapping in helpless terror.

The giant insect reached the platform. Our vehicle had dropped so low I could glimpse its face. Half-humanmonstrous. Its tongue licked out; its great slit of mouth seemed grinning.