"S-sorry, Ryder. She must be under there and I'm blaming her. Excuse me. I'll get on with fixing the lights and power cable."

Ryder watched him go but with mixed feelings. Brian might be a racist, but he could be right about Jena blowing up the mine. Explosives were kept in the stores at the centre, where Jena was seen before the mine blew. She wanted the case destroyed. The loss of contact with her family had unhinged her. He sat on a rock, sending a beetle scurrying into the heather. Jena had too much intelligence to open the case or to attach explosives to it since the virus might survive. She tried to seal it in by blowing the roof down. He stood and walked over to Dan, who was emptying the first trolley load.

"Dan, would Jena know how to use explosives?"

Dan's face showed no surprise. "Her astro-engineering qualifications involved plenty of explosives. She was a brilliant engineer."

"Then, Dan, she is a good engineer," Ryder said. Both men looked for her around the valley and up the mountainside.

Dan took out his cell phone. "You can come down now, Jena. You'll miss dinner."

"Don't you think she should be sent to bed without her dinner?" said Ryder.

"No, she's ten times more irritable when hungry. There she is."

Grubby but with a raised head, she strolled down the mountain to the waiting group. Brian rushed into the mine to tell the rescuers to forget Jena, but to keep going for the case.

Ryder turned his back on her. "Dan, put her under arrest."

"Miss Kochi," said Dan, "consider yourself under arrest."

Megan had already rescued her mountain bike, so Jena walked past the men and carried on down towards the centre.

"Aren't you going to sort her out?" Brian said.

Dan and Ryder looked at each other. How do you admonish a woman as crazy as a hornet-stung bear? In their favour was that she couldn't get at the case now.

Ryder said, "You don't suppose she..."

"Took the case out first? You thought the same thing?" They jumped in the Volvo and drove after her.

"You talk to her, Ryder, she has a soft spot for you."

"You're kidding." It was too late to argue. They'd caught up with her.

"I don't want a lift."

Dan drove off leaving Ryder walking with her.

"You've caused us a lot of difficulty, you know, and worry."

She stopped walking. "You were worried about me? Oh, Ryder."

"We assumed the case had reached a critical phase. When we saw Megan's bike, we thought the case had exploded with you in there."

"What makes you think the case might explode? The first one didn't."

"The first was opened within three days of you finding it. This one was found a week ago. Maybe there's a time limit. Did it look all right to you?"

"I didn't see it. I only blew the roof supports a hundred metres in. You know the case is evil. Satan's blight. I wouldn't want to get near it."

Ryder considered she was telling the truth, so she hadn't moved the case. But there had to be an element of doubt. It was worth continuing the tunnelling to reach the case but also to search the mountainside where she'd been.

"You are coming in with me, aren't you?" Jena said to him. "I might have a concussion and I want you with me, Ryder. I don't think the others like me anymore. You'll help me shower all this rock-dust off me, won't you?"

AWKWARD SILENCES PREVAILED OVER DINNER. If Jena had the sensibilities of a normal person, she would have withered under the evil-eye stares, and haemorrhaged from stabs in the back. However, she remained aloof, secure in her belief that she had saved them from a fate worse than ARIA.

Teresa cornered Ryder in the stores where he was conducting his own inventory of their remaining communications and electronic equipment.

"She's a complete crackpot, Ryder. What are you going to do about her?" She frowned at him with all the body language of a poised mountain cat.

"What do you think we should do with her?"

"Hey, you're the centre leader. That bitch has jeopardised our future. She's a liability. You've always said that to survive, we have to be tough."

"That's true, but I'm not going to put a bullet in a healthy person just because she's temporarily freaked out."

"You mean because she's a child-bearing-age woman and you fancy the pants off her. Why, Ryder, you could put her into solitary with you holding the only visitor's ticket."

"And what about you and the Italian doctor? I don't see you batting his wandering hands away."

"You wouldn't understand. Romantically, he's a million miles ahead of you."

"Teresa, be careful of him. He's sly and a creep. At least with me, what you saw is what you got."

"Listen to you, Ryder. All pompous and above us all."

"If you say so." He was hurt by her barbed comments, but he held back. This community was too small to let bickering get the better of them. Survival was in the balance, and all Teresa wanted to do was score points.

"So what are you going to do with the mad bitch?"

"She can't damage the case anymore, so chill out. I'm in here looking to see if we have an electronic tag we can put on her. Come to think about it, you might have one in your biology equipment?"

Teresa went to a blue plastic container, checked the list of contents printed on the top and waved at it. "Help yourself, but are you sure she wouldn't prefer fluffy handcuffs and for you to whip her ass?"

Again, he held back from retaliating; he had memories of such an S&M scenario with Teresa less than a year ago. She looked at him, letting him know with a wistful look that she remembered that night too. Gone and lost forever.

"Oh, there you are," called Brian from the entrance of the storeroom. "Megan reminded me about something on Llwtymor that might interest you, Ryder."

Glad of the distraction, Ryder followed Brian into the refectory where a hot, black coffee helped him focus on the large-scale map. Brian's grubby finger jabbed at a point halfway from the valley floor to the summit.

"There's an air shaft for the mine that comes out at this spot."

"Really? How does Megan know that? There are no paths around there."

"Fishing," Megan said, who stood behind Ryder.

"What?"

"My dad used to fish the lake, and he brought me. I hated fishing so I wandered all over. Found a propeller blade once. There's an iron grating in the ground up there. Dad said it allowed fresh air into the end of the mine."

"Why couldn't we see the light from it when we were in the mine?"

"Brambles."

"It might not be straight all the way down," said Brian. "But we can find out."

RYDER CARRIED A RUCKSACK AND CLIMBING ROPE, following Megan and Brian up the rough mountainside. Brian had brought a pneumatic bolt cutter that cut through a rusted padlock. Dan and Ryder pulled up the screeching grate until it dropped on its back, crushing thorns. Brian dropped down a lead with a powerful battery lamp while Ryder readied a fish-eye webcam to follow it down on a cable attached to a laptop on the surface. His heartbeat decelerated with relief when the cage with the case showed up on the screen. The group applauded Megan.

"Can we stop working on the tunnel, now?" asked Brian.

Ryder scratched his head. "I suppose so. For all we know, there is a mile of excavating."

"We wouldn't have enough shoring materials anyway," said Brian, relieved to forego more rock clearing.

"So what happens with our time-bomb down there?" said Dan.

"I could get it," Megan said.

"No," Ryder said. "It's safer down there."

"Suit yourself." She stomped off. Brian walked after her.

Antonio said, "Any of us could be lowered and either fetch the case or..."

Ryder pondered and said, "We could be lowered through this aperture and get stuck halfway down."

"I'd be willing to take the risk," Antonio said. "Then of course, if I do get stuck..."

"There'd be one less to feed back at the centre," Ryder said. They all laughed but Ryder meant it.

Dan and Antonio exchanged knowing looks.

"Antonio talked something over with me last night, Ryder," said Dan. "He's volunteering to open the case, alone. Equipped with enough provisions and comms for as long as we think necessary."

Ryder looked at Antonio as if he'd not seen him before. There in front of him was the man making a play for Teresa, hence the lowest form of scum. Yet, he was volunteering for the most dangerous job left on the planet. The opened case could explode, but more likely emit fumes or a virus to complete the task of the disastrous ARIA.

"I'm astounded and incredibly impressed," Ryder said, "but there are many technical issues to resolve."

"I know," Antonio said, "and some made more complicated because of this access point. For instance, how are we to ensure the contents of the case do not escape through this chimney-since that is what it would become?"

"And getting down there, if it is possible without dislocating all your bones, will be easier than the return journey," Ryder said.

"Once down there and after exposing myself to the case, I could occupy myself-in between reporting to you-by clearing a horizontal route through the collapsed roof."

"We might end up losing you under a fresh fall and we'd be back to square one," said Ryder. "I know we couldn't force you not to do what you want, but your health and safety wouldn't be just about you."

"Don't insult me, Ryder. This is a magnanimous situation. With no family left alive and being a physician, I am best placed to help everyone here."

Ryder didn't feel inclined to apologise for his patronising warning. He was used to saying the obvious to some of the centre staff and erred on the side of caution, knowing some would be offended.

"Let's sort out the details back at the centre," he said, knowing Teresa would accuse him of engineering the situation. He could see her wagging finger whooshing through the air, her nagging voice accusing him of throwing her incipient lover down a well. And the joke was that Antonio had thrown himself down. But then maybe he'd been too hasty with the good doctor. After all, his own relationship with Teresa had been rocky for months, and it would have freed him to take up other opportunities. What was he thinking? There were only two other possibilities, Laurette, who had her talons into Gustav, and that crazy, yet mysterious sorceress, Jena.

Tuesday 22 September 2015: Llwtymor Mountain mine.

AT THE BASE OF THE AIRSHAFT, ANTONIO PEERED INTO THE WEBCAM. "Don't forget the champagne on the next drop."

Ryder frowned at Derek, who had been appointed full-time Antonio monitor.

"I think and hope that's another of his jokes. I humour him, Ryder, more than I would you or any of the others because, by God, I wouldn't want to do what he's going to do."

Ryder was pushed out of the way by Megan so she could lower a tightly-rolled sleeping bag, airbed and foot pump all in one bin bag.

Brian and Abdul had set up Antonio's electrical supply, running both a cable from the centre and a car-battery backup trickle-charged by a small wind vane. Solar panels would be ineffective on this north-facing slope. Antonio insisted on a measure of short-term self-sufficiency in case of some disaster at the centre. Water was more difficult to organise. The centre had a filter system using local stream water, but it wouldn't stand storing for weeks without the few bacteria becoming millions. Antonio needed piped water and his own filter along with purification tablets.

Megan trudged off to winch up another load from Teresa, who'd organised a pile of supplies at the base of the slope. From so high up, with so much vegetation and boulders in the line of sight, Ryder couldn't see her. He wondered over her turmoil with her new friend shutting himself away for at least a month's quarantine after the case exposure.

"Watch your back, Ryder," Vlad said, carrying a space-age-looking aluminium cowl to go over the airshaft once they'd finished lowering provisions.

"Are you sure that will work?" Ryder said, fingering the louvers around the cubed piece of modern sculpture.

"No idea," Vlad said.

"He's kidding," Gustav said. "It will prevent rain and animals getting in, let air in and our patent wet-filter system will, hopefully, strangle any alien virus that makes it to this point up the shaft."

"Will it strangle Antonio, if he comes up the shaft?" Ryder said.

"It will be locked from above and below, but he could get out when he needs to via the winch and using tools he has."

Ryder took the Ukrainian away from the shaft for a short walk. "Vlad, the acoustics in that shaft will let Antonio hear conversations at the top."

"So?"

"I thought we laid down the specifications such that he wouldn't just be able to winch himself up and get out without us letting him. There's a danger he might become infected and contaminate us, otherwise."

"Ryder, you have to allow him to get out in an emergency. Suppose after heavy rain, his bit of the mine gets flooded or we get ill and can't get provisions to him? We can't let him die down there."

"The point of quarantine is that it's us who decides when he's to come out." Ryder could feel his cheeks heating but hoped Vlad didn't notice.

"Don't worry. I'm sure he wouldn't without our say so." Vlad returned to fixing the cowl, leaving Ryder seething, then following, plotting another failsafe device. He could understand Vlad being reluctant to trap Antonio in the mine: he'd been with him in a spacecraft for so long. He was like family.

Ryder had to plan for the bigger picture and protect what was left of mankind. He would sort it out with Brian, but he could see where they could fasten the cowl to the grating so that Antonio could only emerge with help from the outside. Keeping it from the others shouldn't be too difficult, and he had no problem letting Antonio out once a quarantine period was complete. If a disaster befell them at the centre, then Antonio would have a problem and might die, but he must have taken that into account when he volunteered. It would not make sense to let him contaminate them if he developed another version of ARIA.

EVERYONE STARED AT THE LARGE MONITOR, watching Antonio's progress. The camera was set up at an oblique angle to see both Antonio and the cage containing the case. He wore a bio-safety suit. Ryder wasn't sure why he didn't wear his space suit, or conversely, why wear any protection when he was there to be exposed?

"Idiot, we don't know what's in the case," Teresa said. "We know he's there as a guinea pig, but there's no need for him to suffer incidental damage."

Ryder could see her point, impressed really, but impatient to witness the events.