Emily found the seat that the computer had assigned her and waited. She stared out of the windows at the forested courtyard. It was like something out of legend: thick evergreens bristling among the leafless birches and oaks, with thin icings of snow on the branches. Even in winter, she could hardly see the other side of the courtyard beyond the trees.

A red light above the desk summoned Emily to the issue counter. A bored librarian held out her hand.

‘Votre carte?’

Emily smiled to hide her anxiety. She held up the card, keeping her thumb over the top half of Gillian’s face to hide it. The librarian barely glanced at it before reaching into a cubbyhole behind her and depositing two books on the counter.

‘I ordered three,’ Emily said in French.

The librarian narrowed her heavily made-up eyes. Before Emily could protest, she swept the card out of her hand and slapped it down on the reader by her computer. She studied the monitor.

‘Anonymous, Physiologus. This book is missing.’ She scrolled down. ‘You have requested this book before?’

‘Um, yes. In December.’

‘And it was missing then, also.’

Was that a question? Emily opted for what she hoped was a suitably French grunt, accompanied by a vague twitch of the shoulders.

‘There is a note on the system that we could not find this book the last time you asked for it.’

Emily rested a hand on the counter to steady herself. ‘I… I just wondered if it might have turned up.’

‘Non.’

‘The online catalogue still shows it as available,’ Emily persisted.

‘Then there is a mistake with the catalogue. I will make another note.’ She lifted her gaze over Emily’s shoulder to the person waiting in line behind her. Emily took the hint.

She went back to her desk with the two books that had come: Studies on the Physiologus and Lost Books of the Bible. Nothing to do with Gillian Lockhart was clear. All she ever saw were distant shadows flitting out of view, uncertain whether they were real or just tricks of the light. She almost felt sorry for Nick.

But she could only work with what she had. She started with Studies on the Physiologus, kneading new facts in with what she already knew. The term ‘physiologus’ had fallen out of use during the Middle Ages, but then revived when new-fangled printers wanted to give their books an old-fashioned stamp of authenticity. The book that hadn’t come was listed in the online catalogue as fifteenth century. Emily flipped to the appendix. There were eleven printed editions of the Physiologus known before 1500. None of them was the one listed in the catalogue.

A dead end. She turned to the other book, the Lost Books of the Bible. This was more of a struggle: she found it hard to engage with the text without knowing what she was looking for. She turned through the pages looking for any pencil marks that Gillian might have made in the margins, any words she might have underlined. She scanned for references to animals, bestiaries or cards; all she got were prophets, ancient kings and angry gods.

She heard a cough behind her and looked round. It was the librarian.

Her heart beat faster. ‘Have you found it?’

The librarian shook her head. ‘There is a message. You must go to the information desk on the upper level. There is a man there to see you – Monsieur Ash. He says it is an emergency.’

The last number Gillian had called from her cellphone was a taxi company. Nick could have rung, but that would have been too quick. This was his last lead; once it was done, he’d have nothing left. So he got the address off the Internet and walked, trying to fool himself for a little while longer that he was achieving something.

He hated the feeling of not knowing what would happen next. Gillian used to tease him that he wanted all life to be like school. ‘If God handed you a schedule for the rest of your life – three periods of work, a half-hour for lunch, forty minutes online, an hour extra-curricular sex – you’d be happy.’ He hadn’t denied it.

Gillian, on the other hand, was spontaneous. Sometimes, when he was too tired to keep up, Nick thought it was almost a neurosis. She’d find a flyer for a concert or an exhibition lying in the gutter and go that night; friends he’d never heard of would call at midnight, just arrived in New York, and she’d scoot out to Penn Station to bring them back to the apartment. She’d meet a guy on a train and be in his apartment at two the next morning playing canasta.

‘People’s lives go like clockwork,’ she told him. ‘They start out buzzing with energy, and by the time they hit thirty they’ve totally run down. If you don’t act, you’re doomed. You need to introduce some random chaos into your life.’

After she left him, he’d seen those flyers blowing down the street and wondered if that was what he’d been. Something she’d found, an impulse acted on to prove she still could. Random chaos.

The taxi office was a small kiosk that had somehow wormed itself into a crevice between two large buildings. There wasn’t much inside: a wilting plastic pot plant, three plastic chairs scarred by cigarettes and two women sitting behind a window in front of a faded map of Paris. Their faces were so heavily made up that they too might have been plastic. Both wore coats, wool hats and fingerless gloves. Each time the phone rang the woman on the left would answer it, bellow a series of questions, then relay the answers to the woman beside her. She in turn would pick up a radio mike and repeat everything the first woman had just said. It looked like the sort of division of labour that only the French could have dreamed up.

Nick went to the window. ‘Do you speak English?’

The radio woman was still shouting orders into her microphone. The telephone woman glanced at him, then jerked her head at her colleague. Nick waited for her to finish.

‘Anglais,’ the telephone woman barked.

The radio woman scowled. ‘A little.’

‘A friend of mine took a taxi on the fourteenth of December. I want to know where she went.’ He looked around, losing confidence. There was no sign of a computer, not even a filing cabinet. ‘Do you have any records?’

The woman stared at him from turquoise lagoons of eyeshadow. ‘Non.’

If he was honest, he hadn’t expected any more. Hope was painful; he was almost grateful to her for killing it off. He turned away.

‘Nom,’ the woman said behind him again. ‘Sa nom. Her name.’

Nick looked back, sheepish as he realised he’d misunderstood.

‘Gillian Lockhart.’

The ring of a telephone interrupted the exchange. The ritual played itself out between the two women. When it was dispatched, the radio woman looked back at him. Closing her eyes, she recited as if into a microphone, ‘Gillian Lockhart. 14.30. From rue Saint Antoine, she comes here.’

Nick looked around the plastic office. ‘Here? Ici?’

The receptionist pointed across the road to a grand neoclassical building. ‘The station. The Gare de l’Est.’

It extended his quest by a few minutes, so Nick walked across the street and into the station. It smelled of diesel fumes and steel. He stared at the banks of monitors on stalks that sprouted from the walls, reading the destinations. He’d always loved European railway stations: the grandiose architecture dimmed with soot, the sleek trains, the destinations that stretched across a continent rather than just safe commuter suburbs. He read the names off the flickering screens. Bâle; Epernay; Frankfurt; Munich; Salzburg; Strasbourg; Vienna.

Where now?

The tongue of the turnstile rolled over and spat Emily out into the foyer. The information desk was ahead of her in the middle of the room. She searched for Nick but couldn’t see him.

She glanced at the glass wall to her right, through onto the balcony that overlooked the forested courtyard. In summer it became a café, packed with tables and chairs; now it was all but deserted. A short man in a silver puffer jacket leaned against the balustrade smoking a cigarette. Was he looking at her?