Susannah McDonald dragged on her cigarette and blew the smoke out slowly, glancing over the swathe of lawn to her left towards the convent. She noticed a few pricks of light in the windows – even if this evening, of all evenings, virtually all the Sisters would be cloistered in their rooms until Sunday, holding private vigils, there was always the chance of someone seeing. She turned the cigarette round in her fingers and shielded the glowing tip behind her palm. The block between the convent and the chapel, where the refectory was, was dark: there'd been an early tea tonight, so the staff could get off for their time off before the Easter Sunday lunch, and Susannah sighed. Unusually for her, she'd forgotten to order supplies to make her own meals over the weekend; she'd have to cadge something off Raffy or Bea.

Raffy and Bea had both been acting a bit strange the last few days. Raffy was very distracted and surprisingly withdrawn since getting back from her sports camp thing; with Raffy, it was usually the pressure of the end of the sports season getting in the way of end-of-year schoolwork – or the other way round. Maybe something was up between her and that sporty lad from the local college she was seeing. She'd always been fine before, though, and there was no reason to suppose this year would be any different, A Levels or no.

Bea'd had a face like thunder at tea. She'd been on her way out as Susannah and Raffy had arrived, and had practically slammed her tray into the trolley near the collection point, which was very unlike her, and probably wouldn't have happened if she'd realised they were there. But then she'd basically ignored Raffy's attempt to catch her attention and ask what was up, too. Bea was never loud or demonstrative, even if she was potentially fuming inside – not that Susannah had ever really seen Bea fuming, either. She was just too quiet and calm. And she never ever ignored someone trying to talk to her – she was just too polite and with her and Raffy, well, they were her friends. The only time Bea did ignore people was when they were trying to bully her: Bea's method of dealing with the bullies was to just pretend they weren't there or were talking to someone else. (And, if she could, just walk away.) Eventually, they did give up, but Susannah often wondered just how much of it Bea took to heart. Not that anyone had dared confront her for at least a year now – one of the perks of being in the Upper Sixth, and a prefect to boot. Bea had quite a lot of power in her quiet way, having not just almost total control over the music in chapel, but also being a Library Prefect. If she wasn't in actual lessons or doing something musical, she was in the library doing her own work while keeping a quietly beady eye on everyone else; Sister Amata, the batty French Sister in charge of the library, relied on her a huge amount, and it was well-known that she listened to Bea like she didn't to many other people – Bea's ability in French probably helped, but she just had a way of dealing with Sister Amata, somehow, that no-one else had found. (Apart from Sister Francesca, probably. No-one, not even eccentric young French nuns, gave her any shit.) So if Bea had grounds to suggest barring you from the library, you were screwed when it came to keeping up with work – and it made Susannah smile sometimes to see how her friend now had such soft power over the people who'd bullied her before, as they all realised exams were getting closer and tried to cram in as much time in the library as possible. Susannah knew they felt Bea was now judging them from a position of righteousness, and though she was certain that Bea was far too fair-minded to actually think of doing so, it pleased her that her friend now unwittingly had the upper hand. She'd definitely been in a real mood at tea, though.

Susannah took a last drag of her cigarette and pushed herself off the buttress she'd been leaning on, brushing the back of her skirt and blazer to get rid of any grit. She ground the butt under her Doc Marten, then carefully buried it a few inches deep in the soil under one of the rose bushes surrounding the east end of the chapel. Sniffing her school jumper, she made sure she'd been careful enough not to get too much of the smell on herself – the security rituals of secret smoking were second nature to her, but it always paid to be careful around this place. Even on Good Friday.

Glancing back at the convent building as she moved off, she noticed the windows of the Mother Superior's office were lit, and could see Sister Francesca in there as well – she wondered why they weren't at their devotions like the rest of the Sisters, but it wouldn't be the first time that something touching on the running of the school and/or priory interrupted the religious life. It must be something to do with the school, if Sister Francesca was involved: as Headmistress she had the final say on school matters, even if technically the Prioress was her superior. Something relatively urgent or serious too, if it needed discussion on Good Friday evening.

The school itself was practically deserted apart from the handful of outgoing and incoming prefects: the Easter holiday was the great hand-over time, when the outgoing Upper Sixth girls showed their Lower Sixth replacements the ropes. Susannah wondered whether it made sense to take the burden of prefectural responsibility off the Upper Sixth's shoulders barely six weeks before they all started sitting A Levels (rather than, say, at Christmas, when they'd have had a chance to actually do some work in time without being distracted), but it was what it was. It was a tradition, and the Catholic Church really went big on tradition.

She checked her watch, and was surprised to see she'd taken longer over her smoke than she'd anticipated – it was twenty-five to seven already. Things on her mind, obviously. To be honest, she really needed to get some revision done, but she'd been fighting shy of the library these last few days, ever since she'd found herself locked in one tea-time a couple of weeks back, and heard the weird sounds coming from the office. When she'd tentatively asked Bea afterwards, Bea'd said it was probably Sister Amata taking her medication – she had some unspecified long-term condition apparently, which involved daily doses of something nasty; she liked to close the library temporarily and get it done out of sight and hearing; it'd obviously been an unfortunate accident that Susie was locked in temporarily that time. Either way, Susannah need to get back into the library and get her head down over her textbooks if she wanted to get her grades: she'd have to check with Bea when was best to avoid bumping into Sister Amata.

She looked over her shoulder at the chapel, but there were no lights on – only the faint flickering of some votive candles. Rounding the chapel's east end to approach the external door to the sacristy, she saw the sacristy windows were dark too. Which meant that Grace – Susannah's replacement as Sacristy Prefect – was late as well. Grace had her own set of keys, unless she'd forgotten them again, but there was no sign of the girl waiting outside. Unless she was in the chapel, waiting in the dark.

Susannah unlocked the external door and flicked the light on with a practised blind reach to the right. She was a tiny bit sorry that this was the last time she could think of it as 'her' sacristy – she wasn't the most pious of girls, but she'd always appreciated the logistics of running an efficient chapel behind the scenes, and had really enjoyed doing a good job of being in charge for the past year – she supposed someone had discerned that potential in her at some point, as it was a responsible position for someone of such shallow faith. Not that Grace was outstandingly pious either but, like Susannah, she was quite organised. Mostly.

After hanging her blazer up on a spare hook near the altar servers' robes, Susannah crossed to the door that led to the chapel and unlocked it, peering out quickly. There was no-one there. From a switch in the sacristy, she put on just the sanctuary lights – all Grace and she needed to do was get things ready for the Easter morning Mass, and have a chat about anything Grace wanted to ask. She'd been Susannah's deputy for a year, so pretty much knew the ropes already, and Susannah quite liked the girl as well as trusting her to step up perfectly well. As Susannah was turning back and heading to the linen chest for a fresh altar cloth, a slightly breathless Grace slipped in through the external door.

The two of them worked with practised efficiency for about twenty minutes, laying out everything that was necessary in the sanctuary and ensuring the sacristy itself was tidy. The only things they left to do first thing on Sunday were to put out the wafers and wine for Communion, and remove the purple shroud over the crucifix. 'I'll come and give you hand on Sunday,' offered Susannah. 'Now, I need to talk you through ordering supplies. Is there anything you want to run over before we do that and I finally hand over the keys?'

'Already got a set of keys.' Grace patted her blazer pocket.

Susannah turned the chapel light off and locked the interconnecting door. She dangled her set by two fingers. 'Ah, but yours doesn't have these ones.' She flicked three smallish old keys nestled amongst the rest and grinned. 'The pyrotechnics cupboard. The Sacristan's desk. And the communion supplies cupboard.'

Grace giggled. Part of her quite liked the idea of being locked in the sacristy with the school's most successful bad girl. (Successful because Susie had somehow always managed to escape heavy punishment for her little rebellions – or had never been caught doing the things she had a reputation for.) 'One thing I was wondering...don't know why I've never thought of this before. But, what do you do if there's only a bit of wine left in the bottle?' The Communion wafers and wine were kept under lock and key, and only the Senior Prefect had that key.

Susannah's grin widened. 'That, Grace, is a bloody good question. There's a correct answer, and there's my answer.' She pointed at the small desk in the nook off to one side of the main space. 'Have a seat, and I'll run through the paperwork and the rest of the boring but important shit, then we can tackle the leftover wine.' The girl took her blazer off and grinned back, moving to sit on the old wooden chair by the desk, flicking her hair over her shoulder and crossing her legs. Susannah leant round her in the cramped space, knocking Grace's knee out of the way with her knuckles gently to unlock the desk, then leant on the wall to one side.

For about ten minutes, Grace and Susannah talked through the process for monitoring supplies and ordering more, and various other bits of necessary admin. The so-called Pyrotechnics Cupboard was really just full of boxes of various candles, matches, incense and the little round charcoal cakes for getting the incense burning in the thurible. The desk where Grace was sat was just used for paperwork. Then Susannah unlocked the supplies cupboard and withdrew two almost-empty bottles of Communion wine from behind an open box of full ones. There wasn't enough in either to be of much use, although too much to just throw away (which was the official advice). 'Father Grady is an absolute bugger for this,' she told Grace. 'The amount of good wine that'd go to waste if that man was left to his own devices.'

'So...?' Grace asked, twirling a strand of hair round her fingers and swinging her crossed leg back and forth. She thought she knew what was coming, and felt the thrill of being under the radar. It was less the actual alcohol, and more being involved in Susie's bending of the rules. And because it was Susie.

'So,' Susannah said, handing Grace the bottles and reaching up to fetch two mugs from the shelf above the desk, 'I don't let it go to waste.' She took the bottles back and shared out the contents between the mugs, pushing one towards her deputy. 'Cheers. Here's to the new Senior Prefect.'

Grace smirked at her, then returned the cheers, and both girls drank a mouthful of the wine. Grace coughed lightly. 'Shit, that's strong stuff if you're not just sipping it.'

'You get used to it. Or mixing it with a bit of water helps. But yeah, it's powerful stuff so be careful not to do this too often. If you want to do it at all. I'm told some Senior Prefects actually have been known to throw the stuff down the drain, believe it or not.' Susannah shrugged. 'Also, don't take the piss with it, yeah? Sister Clare will notice if you order more than's needed.'

Grace sipped more wine, and looked like she was prepared for the taste this time. 'Does Sister Clare have a key as well?'

'Weirdly, no. They give us that responsibility.' Susannah gestured between them. 'Although she is technically the Sacristan.' She drained her mug and held a hand out. Grace did the same and handed her her mug, watching Susannah rinse them under the tap. While her back was turned, Grace undid an extra button on her shirt and twitched her skirt higher up her legs, which she recrossed deliberately as Susannah returned. To her surprise, Susannah didn't replace the mugs on the shelf, but put them on the desk and turned to bring down a small thermal flask from the shelf. Tugging her jumper where it had ridden up a little, Susannah perched herself on the desk and unscrewed the flask. 'Now. Communion wine stinks on your breath, too, so make sure you have mints on you if you're doing that particular little bit of housekeeping.' She poured a small amount of a clear liquid into each mug and re-stoppered the flask. 'Whereas this,' she pushed a mug towards Grace again, 'is much safer.'

Grace sniffed it, and gave a wide-eyed grin, biting her lip. Susie was just as much a bad girl as she'd always thought. 'Vodka? You keep a flask of actual vodka in plain sight in the sacristy?'

Susannah shrugged. 'Gotta be some perks to having the run of the place. And no-one looks for anything naughty in plain sight. Cheers, again.'

Grace shook her head in impressed disbelief, and acknowledged Susannah as she drank. As she leant forward, uncrossing her legs, and put her mug back on the desk, her hand brushed Susannah's skirt – not entirely accidentally. She pushed against the Senior Prefect's leg. 'You actually are as bad-ass as your reputation.' She smirked again, and looked up through her hair. 'Although I can't believe I never cottoned on to this before.' She wiggled the mug, feeling Susannah's skirt move slightly under her fingers. 'I mean, it's not like we haven't worked closely together for a year already.'

Susannah shrugged. 'I'm careful. And I'm not that bad-ass, anyway.'

'Hmmm.' Grace counted off on her spare fingers. 'It's fairly common knowledge you're one of the smokers, although for some reason you're never caught. And you get away with non-regulation hair and non-regulation earrings.' Grace gave up the finger counting and moved the mug into her free hand in her lap. She gestured down Susannah, from her pixie-cut red hair and the double earstuds in each ear, to her diamond-pattern, thin black tights. 'And funky non-regulation tights. And you always get away with having your skirt too short...'

'Think they've just given up calling me on it.'

Grace dropped her hand back onto Susannah's leg, properly this time, and fingered the hem of the older girl's skirt. 'And having people in your room after lights-out.'

Susannah held her breath and stayed very still. 'The rest I'll own up to, but that's definitely not true.'

Grace slid her hand under Susannah's skirt, spreading her fingers out on her thigh. 'Not what I've heard.'

Susannah gently put her hand over Grace's and moved it off her leg. 'Don't know where you've heard that, but it really isn't true. I'm not into girls.'

Grace snorted. 'C'mon, Susie. Practically everyone thinks you really are. Everyone knows you had that thing with your friend...'

'Jesus, Grace. That was like two years ago.' Susannah reached for the flask and took a swig straight from it. 'And it wasn't true then, never mind now. Bea and I didn't "have" anything, apart from our friendship ruined for a while after the rumours went about. I've honestly never done anything with another girl. And I'm sure I can say the same about Bea.'

Grace smirked again, as if she didn't believe it, and sat back, crossing her legs and arms. 'Well, who knows about Beatrice, she's weird. But as for you,' she pointed a finger, 'there's a fair number of girls around here who either want to be you or be with you. There's two of our altar servers alone who have massive crushes on you. Mainly on the basis of your reputation for being so deeply cool, and...you know...fooling around.'

'Not my fault. And I've no idea how I've got that reputation. I've honestly never done anything to justify it.'

'Genuinely surprised you never noticed.'

'Maybe because I wasn't looking for it, because it never crossed my mind? God! This place, sometimes...' Susannah offered Grace the flask, but the younger girl shook her head, redoing the button on her blouse pointedly. Susannah took another sip, then stoppered it again and went to put it on the worktop near the door. 'Just out of interest, what exactly is the story with me and Bea?' She fished some mints from her blazer pocket, taking one then throwing the packet over to Grace.

'Like you weren't there.' Grace popped a mint into her mouth and threw the packet back.

'I genuinely wasn't because there was nothing. But I'm curious to know what's supposed to have happened.'

Grace examined her fingernails. 'You and Beatrice had a thing in Fifth Form, and no-one can ever understand why someone as cool as you'd hang around with such a weirdo, so there must be something going on there, right? Then she got upset because you were a bit of a player, then someone dumped the other one. Who does the dumping changes, depending on who you listen to.'

'Fuck's sake, I'm not a player. Have you ever heard anyone say they've actually been with me?'

Grace frowned. 'To be fair, no...'

'And just now, when you had your hand up my skirt...'

'Yeah, OK.' Grace shrugged. 'But maybe you just don't like me. I mean, with your reputation you could have the pick of about a third of my year, for a start...'

Susannah reached for her flask again and slapped her hand on the counter-top. 'Jesus, Grace. Fuck's sake.' She took a swig of vodka. 'I mean, I like you and you're a nice-looking girl, so you know...if I was actually interested...and up until about ten minutes ago when all this shit started coming out, I respected you as well. If it was going to happen, and I really was that bad-ass, I think we'd have done it long ago, don't you? Probably on that desk, in fact, at least once.'

Grace shrugged in agreement, with a rueful grin. 'Yeah. Probably.' At least Susannah's notorious temper wasn't just a rumour.

Susannah went on, 'Right. So can we lay this fucking stupid rumour about me and Bea to rest as well?' She rubbed her eyes quickly. 'Bea was very kind to me when I came here in Fourth Year, in fact she was about the only person who talked to me normally for about a term. And because she was mates with Raphaela, I suddenly had two friends where I'd had none. Why they like me, I've no idea, but they do. And I'm bloody glad, because they're both fine and decent people.' Susannah felt herself begin to get genuinely angry, but took a deep breath, and another swig of vodka, and composed herself. 'Right. Fuck this. If we're done talking logistics, fuck off. I'll let you have those keys on Sunday.'

Grace realised that she had very little choice, and slipped out of the external door.

Susannah slumped down against a cupboard and swigged some more vodka. She wished she could repair the rips in her friendships with Raffy and Bea, which had appeared back in the Fifth Form – but Bea had just withdrawn into herself completely, never to emerge again fully; and Raffy had been spending the last two years acting as a go-between. Susie was wondering if it was too late, and if not, how to go about it, when a thump and crash from the chapel made her jump.

Heart thumping, she pulled herself up and crossed to the interconnecting door, unlocking it swiftly and automatically flicking the sanctuary light on as she opened it.

Sister Amata was slumped in a pew about a third of the way down, at a very awkward angle. It must have been the weight of her body hitting the pew as she keeled over that caused the thump. Susannah started moving towards her, at the same time as she became aware of the noise of someone descending from the organ loft.

Bea and Raffy appeared, and for an instant Susannah realised there was no-one she'd rather have seen at that moment. Then she glanced down at Sister Amata and saw the sorry state of the nun's habit, streaked with sweat and vomit and piss...and she felt the vodka and communion wine rise quickly to her head. She caught hold of the end of a pew and sat down heavily, suddenly unable to think clearly.

When she could look round, a few moments later, Raffy was running out of the chapel and Bea was gently laying the nun down in the space between the pews. Bea looked up, catching Susannah's eye and holding it for a moment.

'Can you help me?' Bea's voice was hoarse, maybe with the strain of supporting the nun's limp body. Her eyes looked as if she was trying not to cry. 'Recovery position?'

Something inside Susannah was kicked into action by shame at her initial reaction. 'Shit, sorry. Yeah, sure.' She moved round to help Bea move the nun more into the aisle and turn her over onto her front.

While she was sliding the nun's damp, cold hand under her equally clammy cheek, she noticed Bea fumbling some sort of long, slim object out of her blazer pocket. Whatever it was, she kept it hidden in her palm, against her skirt.

'Thanks, Susie.' Bea nodded her head at the main door of the chapel. 'I'll stay with her. Can you go and see if Raffy's got hold of an ambulance? And maybe fetch Sister F, if you can?'

Grateful for something to do that meant the stench of the nun's soiled habit wouldn't mix with the vodka fumes, Susannah got to her feet and went in search of help and her other best friend. As she glanced back into the chapel from the corridor, Bea seemed to have her free hand inside the nun's habit and be readying whatever it was in her other hand, almost as if she was going to stab her.