Those first few weeks it couldn't seem to keep away. Miran almost became afraid to dream. Dreams were when the xenoc ghosts came to haunt him, slipping tortuously through his drowsy thoughts with insidious reminders of the vast atrocity humans had wrought on Jubarra. And when Candice rose to comfort him the xenoc would steal her from him, leaving him to wake up weeping from the loss.

Miran reached the downward slope at the end of the promontory. The nail of the finger, a curving expanse of gently undulating peat, wizened dwarf bushes, and a scattering of boulders. Thick brown water lapped the shore a hundred metres ahead.

The xenoc's presence in his mind was a constant babble. Strong enough now for him to see the world through its weird senses. A murky shimmer of fog with a cyclonic knot approaching gradually. Himself.

«Come out,» he said.

The xenoc hardened itself, becoming one with the land.

«No?» Miran taunted, heady with the prospect of victory. «Well, we'll see about that.»

There were five boulders directly in front of him. Big ochre stones which had fallen from the mountain's flanks far above. Splodges of green lichen mottled their rumpled surfaces. A sprinkling of slate-like flakes lay on the grass all around, chiselled off by a thousand winter frosts.

He lined the laser rifle up on the nearest boulder, and fired. The ruby-red beam lashed out, vividly bright even by day. A small wisp of blue smoke spurted from the stone where it struck, blackened splinters fell to the grass, singeing the blades. The thermal stress of the energy impact produced a shrill slapping sound.

Miran shifted his aim to the second boulder, and fired again.

The third boulder unfolded.

In the camp which housed the ecological assessment team they called them slitherskins, a grudging tribute to the xenocs' ability to blend flawlessly into the background. Rumours of their existence had circulated ever since the primary landing, but it wasn't until the virus was released that a specimen body had been obtained. Some of the xenobiology staff maintained their ability to avoid capture confirmed their sentience; it was an argument the Custodian Committee would rule on when the hearings began.

The few autopsies performed on decomposing corpses found that they had gristle instead of bone, facilitating a certain degree of shapeshifting. Subdermal pigment glands could secrete any colour, camouflaging them with an accuracy terrestrial chameleons could never achieve.

Miran had learned that those in the camp, too, feared the night. During the day the xenocs could be spotted; their skin texture was too rough even if they adopted human colouring, and their legs were too spindly to pass inspection. They were nature's creatures, suited to wild woods and sweeping grasslands where they mimicked inert objects as soon as they sensed danger approaching in the form of the Bulldemons, their natural predators. But at night, walking down lightless muddy tracks between the camp's prefabs, one uncertain human silhouette was indistinguishable from another.

The camp's dwindling population kept their doors securely locked after nightfall.

When it stood up, the xenoc was half a metre taller than Miran. As its knobbly skin shed the boulder's ochre, it reverted to a neutral damp-looking, bluish-grey. The body abandoned its boulder guise, sagging into a pear shape standing on two thin legs with saucer feet; its arms were long with finger-pincer hands. Two violet eyes gazed down at Miran.

Resignation had come to the xenoc's mind, along with a core-flame of anger. The emotions sprayed around the inside of Miran's skull, chilling his brain.

«I hate you,» Miran told it. Two months of grief and venom bled into his voice, contorting it to little more than a feral snarl.

In one respect the xenoc was no different from any other cornered animal. It charged.

Miran let off three fast shots. Two aimed at the top of the body, one dead centre. The beam blasted fist-size holes into the reptilian skin, boring through the subcutaneous musculature to rupture the vitals.

A vertical lipless gash parted between the xenoc's eyes to let out a soprano warbling. It twirled with slim arms extended, thin yellow blood surging from the gaping wounds. With a last keening gasp, the xenoc crumpled to the ground.

Miran sent another two laser pulses into what passed for its head. The brain wouldn't be far from the eyes, he reasoned. Its pincer hands clutched once and went flaccid. It didn't move again.

Distant thunder rumbled down the valley, a sonorous grumble reverberating from one side to the other, announcing the impending arrival of more rain. It reached Miran's ears just as he arrived back at the homestead. There was no elation, no sense of achievement to grip him on the long walk back. He hadn't expected there would be. Fulfilment was the reward gained by overcoming the difficulties which lay in the path of accomplishment.

But Jubarra offered him no goals to strive for. Killing the xenoc wasn't some golden endeavour, a monument to human success. It was a personal absolution, nothing more. Ridding himself of the past so he could find some kind of future.

He stopped by the grave with its high temple of stones to prevent the xenoc from burrowing to its heart. Unbuckling his belt, he laid the laser rifle and its spare power magazines on the stones, an offering to Candice. Proof that he was done here in the valley, that he was free to leave as she'd wished.

With his head bowed he told her, «It's finished. Forgive me for staying so long. I had to do it.» Then he wondered if it really was over for her. Would her ghost be lonely? A single human forced to wander amongst those her race had slaughtered indiscriminately.

«It wasn't her fault,» he cried out to the xenoc ghosts. «We didn't know. We didn't ask for any of this. Forgive her.» But deep down he burned from bright flames of shared guilt. It had all been done in his name.

Miran went into the homestead. The door had been left open, there was a rainwater puddle on the composite squares of the floor, and a chill dankness in the air. He splashed through the water and slipped past the curtain into the hygiene alcove.

The face which looked back from the mirror above the washbasin had changed over the last two months. It was thin, pinched with long lines running down the cheeks. Several days' worth of stubble made the jutting chin scratchy. The skin around the eyes had darkened, making them look sunken. A sorry sight. He sighed at himself, at what he had allowed himself to become. Candice would hate to see him so. He would wash, he decided, shave, find some clean clothes. Then tomorrow he would hike back to the ecological team's camp. In another six weeks there would be a starship to take them off the planet. Jubarra's brief, sorry chapter of human intervention would cease then. And not before time.

Miran dabbed warm water on his face, making inroads on the accumulated grime. He was so involved with the task his mind dismissed the scratching sounds outside, a part of the homestead's normal background noises: the wind rustling the bushes and vegetables, the door swinging on its hinges, distant gurgling river water.

The clatter which came from the main room was so sudden it made his muscles lock rigid in fright. In the mirror his face was white with shock.

It must be another xenoc. But he had felt nothing approach, none of the jumble of foreign thoughts leaching into his brain.

His hands gripped the basin in an effort to still their trembling. A xenoc couldn't do him any real harm, he told himself, those pincer fingers could leave some nasty gouges, but nothing fatal. And he could run faster. He could reach the laser rifle on the grave before the xenoc got out of the door.

He shoved the curtain aside with a sudden thrust. The main room was empty. Instead of bolting, he stepped gingerly out of the alcove. Had it gone into the bedroom? The door was slightly ajar. He thought he could hear something rustling in there. Then he saw what had made the clattering noise.