As one who had been born on Orbitsville, Dallen was anxious for that explanation. For him the sight of the inconceivable expanse of green fire, like a boundless ocean alive with noctilucence, had been the emotional equivalent of a severe earthquake. He had grown up on the Big O, had a primitive unquestioning faith in its permanence and immutability — and now the unthinkable was happening. Tendrils of new ideas were trying to worm their way into his mind and were making him afraid in a way that he had never known before, and it was a process he could not allow to continue. As the minutes dragged by without any word from Lessen his unease and impatience grew more intense. Finally, and not without a twinge of guilt, he took a double-dose hypopad from a locker and placed it on his thumb. He went to Cona and, while overtly trying to make her more comfortable, pressed his thumb against her wrist and fired a cloud of sedative into her bloodstream. As soon as the drug had begun to take effect, rendering her drowsy and passive, he clipped the zero-G webbing across the yielding plumpness of her body and with a reassuring word to Mikel left the cabin.

The standard-issue magnetic stirrups he had fitted to his shoes made walking difficult at first, but by the time he reached the control deck he was moving with reasonable confidence. He found Lessen, Renard and a small group of the ship's officers gathered in front of the view panels, most of which showed luminous green horizons.

"You are not permitted in here," Lessen said to him at once, puffing his chest.

"Don't be ridiculous," Dallen said. "What the hell is going on down there?"

"I must insist that you…"

"Forget all that crap." Renard turned to Dallen with no sign of his former animosity. "This is really something, old son. We talked to Traffic Central and were told that the whole shell lit up like that about five hours ago. Before that, apparently, they had a lot of green meridians chasing each other round and round the surface, but now the illumination is general.

"And you notice the pulsing? They say it started off at about one every five seconds, but now it's up to nearly one a second." Renard grinned at the discrete views of Orbitsville, excited but seemingly untroubled.

It's all part of a process, Dallen thought, remembering his conversation with Peter Ezzati, his instinctive alarm feeding on Renard's lack of concern.

"What did they say about landing?" he said. "How does it affect us?"

"It doesn't. The word from the Science Commission is that the light doesn't affect anything. It's only light. Nothing is showing up on any kind of detector — except photometers, of course — so we just ignore it and go ahead with the landing. They say it's business as usual at all the other entrances."

"I don't like it" Lessen said gloomily.

Renard clapped a hand on his shoulder. "You don't have to like it, old son. All you have to do is fly my ship, so I suggest you get on with it without wasting any more valuable time. Okay?"

"If you don't mind," Dallen said, "I'd like to stay here and watch."

Renard made a sweeping gesture. "Be my guest."

Lessen swelled visibly, looking as though he would protest, then shrugged and with a practised zero-G shuffle moved to a central console. He keyed an instruction to the snip's computer. A few seconds later Dallen felt a faint tremoring in the deck and glowing jade horizons changed their attitudes as the secondary drive came to life. A short time later Portal 36 showed up on the forward screen, visible at first as a short dark line floating in the green luminescence. The line grew longer and thicker, developing into a widening ellipse which quite abruptly became a yawning aperture in the Orbitsville shell.

Dallen, in spite of knowing what to expect, felt a coolness coursing down his spine as he saw the blue — the impossible blue — of summer skies within the portal. For a moment he had an inkling of how Vance Garamond and his crew must have responded two centuries earlier when their flickerwing nosed its way into the shaft of sunlight radiating into space from the historic Portal 1. As the aperture became a perfect thousand-metre circle of azure, Orbitsville's interior sun swam into view and stayed at the centre.

Without quite knowing why, Dallen found himself having to bunk to clear his vision. I should have been with Silvia for this, he thought, wondering if she was in the Deck 3 observation gallery.

"We're locked on station at an altitude of two thousand metres," Lessen said, glancing at Dallen to see if he was absorbing the information. "Beginning our descent now."

Dallen gave him a friendly nod, accepting the verbal peace offering, and watched the circle expand in a lateral screen. The descent was slow but continuous, and after fifteen minutes the separation between the ship and its destination had been reduced to tens of metres. Propelled and maintained in the docking attitude by computer-orchestrated thrusters, the Hawkshead was lowering itself towards one edge of the aperture. Sting-like grapples were projecting beneath the central hull, ready to clamp the ship in place. At any of Orbitsville's principal ports it would simply have been a matter of sliding into one of the huge docking cradles, but here it was necessary for the ship to find its own anchorage.

The final step, Dallen knew, would be to extend a transfer tube from an airlock and drive it through the diaphragm field which kept Orbitsville's atmosphere from spewing into space. He estimated that unloading the grass and seed samples could take no more than a day, and from that point on Silvia and he would be free to…

"I don't like this," Lessen announced, speaking with a studied calmness which had the effect of momentarily stopping Dallen's heart. "Something doesn't add up."

As if to ratify the captain's statement, crimson and orange rectangles began to flash on the control console to the accompaniment of warning bleeps. Two of the ship's officers moved quickly to separate consoles and began tapping keys with quiet urgency. The deck stirred like an animal beneath Dallen's feet.

Renard cleared his throat. "Would somebody care to tell me what's going on? I do own this thing, you know."

"The thrusters are still delivering power," Lessen said. "But the ship has stopped moving."

"But all that means is…" Renard broke off, his coppery eyebrows drawing together.

"It means something is counteracting the thrust — and our sensors can't identify it. We have a separation of twenty eight metres between the shell and the datum line of the hull, so there is no physical obstruction, but we can't detect any field-type forces. I don't like it. I'm going to back off."

"There's no need for that," Renard said. "Push a bit harder."

The officer at the smaller console to Dallen's left raised his head. "There's no indication of any threat to the ship."

"I don't care," Lessen replied, strutting nervously like a dove. "Traffic Central said conditions were normal at all other portals, but they can't vouch for anything here. We'll have to dock somewhere else."

"Lake hell we will," Renard said. "I've got an agricultural station and a team of bloody expensive research workers waiting for me down there. We’re going in right here."

"You want to bet?" Lessen palmed a master control with showy vigour, asserting his authority.

Watching him closely, Dallen saw a look of spiteful triumph which lasted only a few seconds and vanished as the patterns of red and orange on the console changed. New audio alarms began an insistent buzzing. Dallen felt vulnerable and totally helpless as he tried in vain to interpret the various information displays around him. it's all part of a process, came the fugue-thought. Orbitsville doesn't catch fire for nothing…

"We're not gaining any altitude," the officer on his left said.