Northanger Abbey. Val McDermid

      Mr Allen grunted. ‘Probably.’ He made a performance of closing his newspaper and draining his cup. ‘I’ve got a ticket for a show at half past ten at the Pleasance. A sketch comedy group from Birmingham doing a musical version of Middlemarch.’

      ‘That doesn’t sound very likely.’

      He stood up and stretched. ‘And that, my dear Cat, is precisely why it might just work.’

      Cat realised she still had a lot to learn about contemporary theatre. With luck, she’d know much more by the end of her four weeks in Edinburgh. ‘Are we coming with you?’

      He chuckled. ‘God, no. Susie won’t venture anywhere near a cultural event until she’s kitted herself out in this season’s wardrobe. You two are destined for the shops this morning. I hope you’re feeling strong.’

      At the time, she’d thought he was exaggerating, as she knew men are inclined to do on the subject of women and shopping. But by the fifth shop, the fifth pile of clothes, the fifth changing room, Cat was beginning to feel amazement at Mr Allen’s level of tolerance. Admittedly, she’d had little opportunity to observe married life at close quarters, apart from that of her parents. But although she didn’t like herself for the thought, Cat reckoned she had somehow previously missed the realisation that Susie Allen was the most empty-headed woman she’d ever spent time with. What was bewildering about this discovery was that Mr Allen was definitely neither empty-headed nor obsessed with how he looked. It was puzzling. All they seemed to share was curiosity. But while Mr Allen’s curiosity was aimed at finding new wonders to bring to the public’s attention, Susie Allen seemed interested only in spotting famous faces among the crowds that thronged the shops and the streets of Edinburgh.

      ‘Isn’t that the little Scottish woman who’s always on the News Quiz? Oh, and surely that’s Margaret Atwood over there, trying on hats? Oh look, it’s that rugby player with the big thighs.’ Such was the level of Susie’s discourse.

      Her one saving grace, at least to a teenager, was her generosity. While she lavished a new wardrobe on herself, Susie was not slow to treat Cat to similar delights. Cat was not by nature greedy, but there was never much to spare in the Morland family budget for the vanity of fashion over practicality. Although Cat knew it was generosity enough to bring her on this trip and that her parents would disapprove of her accepting what they’d regard as unnecessary charity, she couldn’t help but be seduced by the stylish trifles Susie thought her due. Even so, by mid-afternoon, Cat was weary of retail therapy and longing to plunge into some cultural life.

      Her prayers were answered when they returned to the flat to find Mr Allen sitting by the window with a cup of tea and his iPad. ‘I have tickets for you both for a comedy show this evening at the Assembly Rooms,’ he announced without stirring. ‘I’ve been invited to a whisky tasting, so I’ll meet you in the bar after the show.’

      Cat retreated to her room, where she spread her new clothes on the bed and photographed each item with her phone. She posted her favourite shot – a camisole cunningly dyed in gradations of colour from fuchsia to pearly pink – on her Facebook page then sent the others to her sisters. She texted her parents to say she’d spent the day walking around with Susie and they’d be going out to see a show in the evening. Instinctively, she knew what not to tell her parents. Sarah and Emily wouldn’t give her away. Not because they were intent on keeping her confidences, but rather because their annoyance at what they were missing out on would manifest itself in blaming their parents.

      The pavement under the triple-arched portico of the Assembly Rooms was busy with people milling around, eyes darting all over the place, eager to spot acquaintances or those they would like to become acquainted with. Posters plastered every surface, over-excited fonts trumpeting the attractions within. Everything clamoured for Cat’s attention and she clung nervously to Susie’s arm as they pushed through the crowds to get inside.

      The scrum of people seemed to grow thicker the further they penetrated the building. Mr Allen had spoken of the grace and elegance of the interior, explaining how it had been restored to its eighteenth-century glory. ‘They’ve kept the perfect proportions and returned it to its original style of decoration, right down to the chandeliers and the gold leaf on the ceiling roses,’ he’d told them over their early dinner. Cat had been eager to see it for herself, but it was too crowded to form any sense of how it looked. In between the heads and the hoardings she could catch odd glimpses here and there, but it formed a bewildering kaleidoscope of images. The sole impression she had was of hundreds of people determined to see and be seen on their way to and from an assortment of performances.

      ‘I know where we’re going.’ Susie had to raise her voice to be heard in the throng. She half-led, half-dragged Cat through the crowd until they finally reached their destination. Susie handed over their tickets and they were admitted to the auditorium.

      This was not Cat’s initiation into live performance. She’d regularly attended performances in the village hall and even, occasionally, at the Arts Centre in Dorchester. She knew what to expect. Rows of seats, a soft mumble of conversation, a curtained proscenium arch.

      Instead, she was thrust into a hot humid mass of bodies that filled the space around a small raised dais at one end of the packed room. Through the gloom, she could see some chairs, but they were all taken. What remained was standing room only. Standing room so tightly packed that Cat was convinced if she passed out, nobody would know until they all began to file out and she crumpled to the floor.

      ‘It’s a bit hot,’ she protested.

      ‘You won’t notice when the show begins,’ Susie assured her.

      Because Susie had taken so long to get ready, they were only just in time. A skinny young man with a jack-in-the-box spring in his step bounced on to the stage, his hair a wild shock of blond and blue that matched his T-shirt. He dived straight in with a barbed attack on his arrival in Edinburgh, his West Midlands delivery so fast and so heavily accented that Cat could barely make out one line in three.

      The audience seemed to fare better, following the performance well enough to cheer, laugh and heckle in equal measure. It was a novel experience for Cat, and in spite of her discomfort, she found herself caught up in the atmosphere, clapping and laughing regardless of whether she’d got a particular joke.

      Eventually the show came to an end, with whoops and cheers signalling that it had been more of a success than not. The one good thing about being so far back was that they were able to make a relatively quick getaway. It was almost dizzying to emerge into the relative airiness of the foyer after the closeness of the event. ‘The bar,’ Susie said, immediately dragging her away from the direction of the street and deeper into the bowels of the building. ‘I’m gagging for a drink.’

      The bar was no less crowded. People stood three deep waiting to be served. Susie groaned and glanced at her watch. ‘Andrew will be here any minute; he can do the donkey work for us. Come on, let’s find a seat, my feet are killing me.’ Cat wasn’t surprised. Even a teenager would have had more sense than to go out for the evening in the ridiculous shoes Susie had bought that morning.

      Finding a seat didn’t seem a likely prospect to Cat, but Susie was undaunted by the crowds. She spied a table occupied by a group of young people who were clearly together, bunched around wine bottles and glasses. Susie marched straight up to the table and plonked herself on the end of the banquette. ‘Squeeze up, darlings,’ she said, waving her hands in a shooing motion.

      Despite their anarchic appearance, this was evidently a group of nicely brought-up students. They obediently squashed closer together, creating just enough space for Susie and a sliver of seat for Cat. But politeness didn’t extend to including the pair in their conversation. Cat felt invisible and unattractive. All at once it dawned on her that she had never been in a crowded place where she didn’t know most of the other people present. It was simultaneously thrilling and unnerving. The potential for romance or danger was all around her; it was time to embrace the unfamiliar, not shrink from it.

      She turned to share her insight with Susie, who was scouring the room with a pout on her face. ‘Unbelievable.