'It's Andromeda.'

'Is that a star? Looks a bit like a hamburger.'

'It's a whole galaxy.'

'f.u.c.k, so it is,' Cameron says. 'Like a flattened disc.'

'The Earth wasn't flat, but it turned out the universe is,' Matt mumbles.

'Messier 31,' Adnan informs them. 'Two hundred thousand light years across. It's the nearest galaxy to here, and it's heading towards us on collision course at three hundred thousand miles an hour.'

'f.u.c.k!' Cameron shouts, and dives theatrically out of the way, prompting much hilarity.

'Don't sweat. It's two and a half million light years away. We've got three billion years before impact.'

'Nothing can travel faster than light,' Radar says. 'I remember Mr Kane telling us that. So that means humans are never going to reach these places, are we?'

'Not travelling on a linear plane, no. In fact, the universe is expanding at such a rate of acceleration that the light from the more distant parts of it will never reach us. But that's only talking about movement in three dimensions.'

'Well what other dimensions could you be talking about?' Radar asks. 'The fifth one, with Mr Mxyzptlk from Superman Superman?'

'Physicists are increasingly accepting that there may be higher dimensions, as well as parallel universes.'

'Seriously?' Cameron asks, lifting his head from the scope and letting Ewan jump in.

'Straight up,' Adnan a.s.sures him. 'Our universe could be a four-dimensional island floating in higher-dimensional s.p.a.ce, one of an infinity of islands, in fact. But the thing about this higher dimension is that if we could see it, if we could move through it, we'd have a very different concept of distance.'

'How?'

'Well, think about an ant on this duvet.'

'More like a flea if it's Radar's,' Ewan suggests.

'Shut it you, ya fudnut.'

'The point is, the ant is only moving in two dimensions: width and length. It can't access - and isn't even aware of - what is effectively a higher dimension: height. So if there was a group of ants on this duvet and you picked one up, it would look to its mates like it had dematerialised. You put it down again on the other side of them, and it looks to the ants like it's been teleported. But all that's happened is it's moved through a dimension the ants can't see and aren't aware of. We move in three dimensions, plus the dimension of time, but if there was a fifth dimension, the same effect could apply to us.'

'You could perform surgery without breaking the skin,' says Matt, grasping the principle and expanding on it in his familiarly skewed way. 'To a fifth-dimensional being, our anatomy would look like a cut-away diagram.'

'But how would we cover distance quicker?' Radar asks. 'The ant still has to travel - it hasn't taken a short-cut.'

'There's a limit to the a.n.a.logy,' Adnan admits. 'But if you can imagine, our perception of three-dimensional distance might not reflect reality, just like the ant's perception of two-D distance. Look at this.'

Adnan takes a corner of the duvet in his hand.

'The ant is here, right, at one end of this wee universe. To get to the opposite corner, it's a long distance in two-D s.p.a.ce, isn't it?'

'Aye,' Radar and Cameron agree.

'Now watch this.'

Adnan folds the duvet diagonally until the opposite corners are held only an inch apart. 'The distance in two-D s.p.a.ce remains the same, but the distance in three-D s.p.a.ce is much shorter.'

'Wow,' Cameron says. 'That's just . . .'

Adnan witnesses Cameron's awe in HUD-mode for a moment. He pictures the word OVERLOAD flashing across the screen, counter bars pulsing into the red zones at either side.

'We think of s.p.a.ce as a place,' he continues, 'or even an absence of material, but scientifically you need to think of it almost like a substance itself. That's why parallel universes, if they exist, could be only a molecule's width apart from our own: a universe creates its own s.p.a.ce.'

In Adnan's HUD, Cameron's head actually explodes.

Guthrie has a darkening glower about him, sighing with a dissatisfaction that appears to be growing in proportion to his obvious efforts to refrain from expressing it. There's been a weird atmosphere since Kane left, exacerbated by it being his bedroom that they're sitting in. Kane had allowed Guthrie the last word and perhaps tactfully chosen that moment to withdraw, but he knew that Guthrie's values would be affronted that they were even having such a discussion at all. Consequently it feels to Blake a bit like Kane farted and then left everyone else to smell it.

'I should have gone for Beansy,' Blake says, harking back to the sweep to lighten the mood. 'Schoolboy error picking Roxburgh. Too grown-up these days, or aspiring to be.'

'Yep,' Heather agrees. 'That's why I went for Deso. Unapologetically juvenile. Dan's on a decent shout with Radar.'

But Guthrie's not going to be soft-soaped.

'With all respect, Father Blake, I think it's high time you stopped apologising for your church and started standing up for it. All this so-called atheism is just a fashion, a trend. They know the truth deep down and that's why they all change their tune as soon as they realise they need need G.o.d.' G.o.d.'

'They don't seem to be realising it in great numbers,' Blake replies softly. 'My growing fear is that I'm part of a dying way of life. How many kids who've been through St Peter's in your time ended up becoming priests?'

'That's just my point, Father. Secular influences: it's not trendy. But trends are localised. There's no shortage of priests coming through from the developing world, where they're less worried about their hairstyles, or what's being said about them on each other's web pages.'

'Yes. The priesthood is a popular vocation where there's ma.s.s poverty, low literacy and limited access to communications technology. That isn't telling me the same good news as it's telling you.'

'Of course, there is a simple solution,' Heather ventures.

Guthrie turns towards her with genuine interest. It's clear he has no idea what she's about to suggest, which is entirely the point she's making.

'What's that?'

'Start ordaining women.'

Guthrie sighs with irritation, like he was genuinely hoping to hear something constructive but has instead merely received another 'anti-Catholic' jibe. However, it's Blake whom Heather decides to put on the spot about it.

'Why not?' she asks him. 'Do oestrogen levels interfere with the process of transubstantiation?'

'No, we're concerned that you'll start knitting in the middle of ma.s.s, or giving sermons about shoes.'

'Seriously, Con, why not?'

She's looking at him with something he just can't read. There's a mischief, a toying about her, and yet there's something else she wants from him, an invitation to break ranks on her behalf.

'Jesus didn't pick women. He created a priesthood of men.'

'That's the party line. What do you you believe?' believe?'

'Any priest who declares in favour of female ordination would be doing so against the Deposit of Faith: the body of unchangeable teachings entrusted by Christ to his apostles.'

He hopes she hears his real answer, encoded in the word 'would', but if so, she doesn't look satisfied.

'I think the Church would rather crash and burn than cave in on that one,' she opines.

'It would crash and burn if it did cave in,' declares Guthrie. 'Because it wouldn't be the Church any more. That's what the modernists and apologists don't understand. We can't start throwing the baby out with the bathwater. If we keep bowing to transient values just to be popular, then we end up giving away the farm.'

Heather puts down her gla.s.s, still with the best part of a measure in it, and stands up.

'I suffer not a woman to teach, nor to usurp authority over the man, but to be in silence,' she says. 'But in defiance of the Book of Timothy, being a teacher, I'm away to shout at Kane to get a shift on.'

And then there were two.

Guthrie pours himself another shot from Kane's bottle, while Blake braces himself for a sustained onslaught that he really can't be bothered with after a long day. Instead, however, Guthrie necks it in one and gets to his feet.

'I'm for my cot,' he says, stretching.

Before he goes, though, he puts a paternal hand on Blake's shoulder.

'Stand fast, Father,' he says. 'Take strength from the Lord. This church has endured for two thousand years, and it's had harder things to face in that time than the goggle box and the internet. It's G.o.d's will, and none can oppose it.'

Blake gives him a smile and a nod that he hopes look convincing.

I wish I had your faith, he thinks. I wish I had your faith.

'How's things on the distaff side of the fire doors?' Kane asks.

'Calm,' Heather tells him. 'Winding down into late-night blethers mode. I'm just putting in an appearance for show: I think both sides know who's going to crash out first.'

'Aye. We can get our revenge in the morning, though. Wake them up early and kick in their hangovers.'

Heather realises he's only half joking. Despite dire announcements about being sent home instantly if booze was found on them, everybody knew it would still be flowing, even Guthrie. It was a matter of entrusting the kids to police themselves: it wouldn't be an issue unless any of them were daft enough to make it one.

They're walking slowly along the link corridor that forms an alternative route back towards reception, avoiding a trip back through the boys' corridor. It's fairly quiet, just the occasional burst of laughter.

'You're fifteen quid up, by the way,' Blake tells her. 'The sweep.'

'Oh, nice. I'll put it towards more malt. Actually, on second thought . . .'

'Yeah,' Kane says, a hint of a blush about him. She expected him to be unapologetic, even perversely proud of starting a rammy, but she sees something else. It's as though he's been caught doing something, and she thinks she knows what it is.

'I used to think that Guthrie got on Con's case, but I'm starting to realise: Dan's a p.u.s.s.ycat compared to you.'

'It's not what it looks like,' he insists. 'Con and I go way back. We've been friends since before we were the age of the kids here. We like to b.u.t.t heads, philosophically, but it's just a debate, albeit an endless one.'

'It looked like more than that to me,' Heather says.

'Don't worry about it - there's no animosity, I can a.s.sure you.'

'I believe you. What I saw was the opposite of animosity. You were impa.s.sioned. It was like Blake's an alcoholic and you're his best friend staging an intervention.'

Kane opens his mouth as though to offer a denial, then lets out a regretful sigh. Busted.

'You guys were at school together. Catholic school. But one day you saw the light and you've been trying to save him ever since?'

'That would be one way of looking at it,' he concedes. 'Except I don't tend to regard it as being me that had a conversion. It was growing up talking to Con about things that set me on my heretical way. He was always a deep thinker about these matters; about all matters. Smartest guy I've ever known.'

'But if the smart guy turns religious, you reckon something's gone wrong? Doesn't that seem a little arrogant?'

'It would if that was the whole story. Someone once said that "the reason smart people believe weird things is that they are skilled at defending beliefs they arrived at for non-smart reasons". Usually that reason is that they were told this belief at an early and impressionable age by someone they trusted to tell them the truth. Then decades of reinforcement weave a web that is very difficult for the individual to pick apart because it's like performing surgery on yourself. With Con, I'm determined to keep picking at the web for him, stop it from hardening.'

'Because you think a "non-smart" reason lies at the heart of his faith. Sorry, but that still sounds incredibly arrogant.'

'Like I said, it's not the whole story.'

'I heard he was once engaged before he decided to become a priest. Is that part of the story?'

Kane has a glance back along the corridor, as though checking there aren't a dozen kids sneaking up on him. They're approaching reception. With a troubled look on his face, he nods towards a couple of couches, and they sit.

'Blake met this girl Gail in second year at uni, met her through me. She and I were at Strathclyde, Con was at Glasgow. She was studying law, but she said she'd no great desire to be a lawyer. Con was different: he didn't know what he wanted to do before he went to uni, then once he got there, he just knew he didn't want to leave. He enjoyed learning and he enjoyed teaching. By third year he was already paying back his student loan by tutoring kids for their Standard Grades and Highers. The guy just loved academia. He also loved Gail. The two of them were sickening, in fact, back then. I'd be going from one disastrous relationship to another and they were love's young dream.'

Kane grimaces a little, like he's suffering acid reflux and will have to re-swallow something bitter.

'Just a f.u.c.king waste,' he says. 'Thinking of what he could have had. What they they could have had.' could have had.'

'So what prompted this dramatic change of path? Never mind that, what about Gail: if they were engaged, how did the poor girl take him ditching her to join the clergy?'

Kane swallows, and it's as bitter as he antic.i.p.ated.

'She dropped dead on a squash court two days after Con sat the last of his finals. Undiagnosed cardiac defect.'

'Christ.'

'I can't begin to imagine what Con went through, and in my opinion, he never recovered. I think he joined the priesthood in the same way that men used to join the Foreign Legion.'

Kane's eyes fill, though he's talking about things that must have happened well over a decade ago.

'He would probably have described himself as agnostic before Gail died. We were both brought up Catholics, but the difference between us was that while I was happy to have extricated myself and given it up as a bad lot, Con was regretful that the Church couldn't answer his questions. He hadn't been to ma.s.s in years, but it was like he was always leaving the door open just in case the Church could improve its case. Then he suddenly finds himself trying to make sense of what had happened to Gail, contemplating the loss of this whole future that had been in front of him one minute and taken away forever the next. He needed to believe in something, needed to believe there was a reason or an order behind it, and a purpose for himself in the world after being cut adrift. That's his "compelling but non-smart" reason for turning to religion.'

'But whether you like it or not, it was religion that got him through it,' Heather says. She speaks softly, trying to ensure it doesn't sound like she's telling him off or taking sides, but she's already conscious of wanting to protect Blake. 'You have to give credit where it's due. Con is happy in what he does. He's good at what he does. He could never get back what he lost, but what he's got today, he's got because of his faith. Maybe you should try to make peace with that.'