Garamond raised his eyebrows. “What have you done to it?”

“All I’ve done is fix it.” Yamoto gave a quivering, triumphant grin as two more tapping sounds were heard almost simultaneously.

“Then what are those noises?”

“Those, my friend, are delta particles going through our screen.” The astronomer’s words were punctuated by further noises from the machine. “And their frequency indicates that we are close to their source.”

“Close? How close?” Yamoto took out a calculator and his fingers flickered over it. “I’d say about twenty or thirty thousand kilometres.”

A cool breeze from nowhere played on Garamond’s forehead. “You don’t mean from Beachhead City.”

“Beachhead City is the only source we know. That’s what it’s all about.”

“But…” A fresh staccato outburst came from the detector as Garamond, knowing he should have been excited, looked out through the front windshield of the aircraft at a range of low mountains perhaps an hour’s flying time ahead. They seemed no more and no less familiar than all the others he had seen.

“Is this possible?” he said. “Could we have overestimated the flight time by two years?”

Yamoto turned an adjusting screw on the delton detector, decreasing the sound level of its irregular tattoo. “Anything is possible on Orbitsville.”

It was late on the following day when the two stiff-winged, ungainly birds began to gain altitude to cross the final green ridges. All crew members, including a fever-eyed O’Hagan, were gathered to watch as the mountain crests began to sink in submission to their combined wills. Changing parallaxes made the high ground below them appear to shift like sand.

Yamoto switched off the detector’s incessant roar with a flourish. “The instrument is no longer of any use to us. Astronomically speaking, we have reached our destination.”

“How far would you say it is, Sammy?”

“A hundred kilometres. Perhaps less.”

Joe Braunek squirmed in his seat, but his hands and feet were steady on the flying controls. “Then we have to see Beachhead City as soon as we clear this range.”

Garamond felt the conviction which had been growing in him achieve a leaden solidity. “It won’t be there,” he announced. “I don’t remember seeing a mountain range this close to the city.”

“It’s a pretty low range,” Yamoto said uncertainly. “You wouldn’t have noticed it unless you had a specific…”

His voice faded as the ground tilted and sloped away beneath them to reveal one of Orbitsville’s mind-stilling prairies. In the hard clean light of the sun they could see to the edges of infinity, across oceans of grass and scrub, and there was no sign of Beachhead City.

“What do we do now?” Braunek spoke with a curious timidity as he looked back at the other three men. The resilience which all the months of flight had not been able to sap now seemed to have left him. “Do we just fly on?”

Garamond, unable to feel shock or disappointment, turned to Yamoto. “Switch the detector on again.”

“Right.” The astronomer reactivated the black box and the cabin immediately filled with its roar. “But we can’t change what it says — we’re right on target.”

“Is it directional?”

“Yes.” Yamoto glanced at O’Hagan, who nodded tiredly in confirmation.

“Swing to the left,” Garamond told Braunek. “Not too quickly.” The plane banked slowly to the north and, as it did so, the sound from the delton detector steadily decreased until it faded out altogether.

“Hold it there! We’re now flying at right angles to the precise source of the particle bombardment. Right, Sammy?”

Yamoto raised the binoculars and looked in the direction indicated by the aircraft’s starboard wing. “It’s no use, Vance. There’s nothing there.”

“There has to be something. We’ve got an hour of daylight left — take a new bearing and we’ll follow it till nightfall.”

While Yamoto used the lightphone to bring the second crew up to date on what was happening, Joe Braunek steered the aircraft on to its new heading and shed height until they were at cruise altitude. The two machines flew onwards for another hour, occasionally swinging off course to make an up-dated check on their direction. Towards the end of the hour O’Hagan’s strength gave out and he had to be helped back to his bunk.

“We messed it up,” he said to Garamond, easing himself down.

Garamond shook his head as he covered the older man’s thin body. “It wasn’t your fault.”

“Our basic premise was wrong, and that’s unforgivable.”

“Forget it, Dennis. Besides, you were the one who warned me we had no right to pick up that first particle so soon. As usual, you were right.”

“Don’t try to butter me. I’m too…” O’Hagan closed his eyes and seemed to fall asleep at once. Garamond made his way back to the cockpit and sat down to weigh up the various factors involved in the ending of the mission. He sensed that the resistance of the other men, which had surprised him earlier, would no longer be a consideration. They had allowed themselves to hope too soon, and Orbitsville had punished them for it. What remained now was the decision on where to make the final landing. His own preference was for the foothills of a mountain chain which would provide them with rivers, variety of vegetation and the psychologically important richness of scenery. It might be best to turn back to the range they had just crossed rather than fly onwards over what seemed to be the greatest plain they had encountered so far. There was the possibility that something could go wrong with one of the aircraft when they were part way across that eternity of grass; and there was the certainty that what they would find on the far side would be no different to what they had left behind. Unless they came to a sea, Garamond reminded himself. A sea would add even more…

“I think we’ve arrived,” Braunek called over his shoulder. “I see something in front of us.”

Garamond moved up behind the pilot and peered through the forward canopy at the flat prairie. It stretched ahead, unbroken, for hundreds of kilometres. “I don’t see anything,” he said.

“Straight ahead of us. About ten kilometres.”

“Is it something small?” “Small? It’s huge! Look, Vance, right there!”

Garamond followed the exact line of Braunek’s pointing finger and a cold unease crept over him as he confirmed his belief that they were looking at featureless flatlands.

Yamoto shouldered his way into the cockpit. “What’s going on?”

“Straight ahead of us,” Braunek said. “What do you think that is?”

The astronomer shielded his eyes to see better and gave a low whistle. “I don’t know, but it would be worth landing for a closer look. But before we go down I want to get an infrared photograph of it.”

Garamond examined the sand-smooth plain once more, and was opening his mouth to protest when he saw the apparition. He had been looking for an object which distinguished itself from its surroundings by verticality and texture, but this was a vast area of grass which differed from the rest only in that it was slightly darker in colour. It could have been taken for a natural variation in the grass, perhaps caused by soil composition, except for the fact that it was perfectly circular. From the approaching aircraft it appeared as a ghostly ellipse of green on green, like a design in an experimental painting. Yamoto opened his personal locker, took out a camera and photographed the slowly expanding circle. He reeled the print out, glanced at it briefly and passed it round for the others to see. On it the area of grass stood out darkly against an orange background.

“It’s quite a few degrees colder,” Yamoto said. “I would say that the entire area seems to be losing heat into space.”

“What does it mean?”

“Well, the grass there is of a slightly different colour to the rest — which could mean the soil is absorbing some mineral or other. And there’s the heat loss. Plus the fact that radiation from the outside universe is being admitted… It adds up to just one thing.”