Their Paris section was never quiet. With the Sorbonne University, the glittering Luxembourg pleasure gardens and the now defunct Cordeliers Club all within a stone’s throw, the streets were always busy. Shops and cafés opened until late at night, their awnings hanging over cobbled roads lined with crooked townhouses, three, four, five storeys high. They sank against their neighbours, plaster flaking from the stone and water dripping from broken gutters. The once fine gardens and facades of the old hôtels of the aristocracy had fallen into disrepair, spilling weeds and dead branches into already-clogged drains. The ghost of their former glory still haunted the city in the elaborate stone curlicues above the doorways, the wrought-iron balconies and slate-grey roofs. People filled the streets; young girls selling wilted cress, opium addicts slumped in dark doorways and street sellers hawking fortunes and rosaries in equal measure. Glamorous young wives bought spools of ribbon and lace as polished gilt carriages clattered past pristine glass shop fronts, disgorging the petit bourgeoisies into the law firms and counting houses. Ada stepped from cobblestone to cobblestone, holding her dress up out of the muck that flowed freely along the street.

Being in James’s company made her heart feel raw, but she couldn’t deny that some masochistic part of her was desperately curious about him. This boy Camille had selected before her. She looked him over as they walked. Tall, broad-shouldered, a lick of hair curling into his eyes. With his hat and coat brushed clean and buckles shining on his shoes she could see how expensively he dressed, how his cream linen waistcoat and breeches were tailored carefully to fit.

They gave the Conciergerie a wide berth and crossed the Île de la Cité at the far end by Notre Dame, the bridge lined on either side by jumbled black and white timber-frame houses. It was early evening, and the long summer days meant sunset was way off.

‘Is Cam always so tense these days?’ asked James as they reached the Right Bank.

There he was again, talking about Camille as if he owned everything about her. The familiarity of the nickname, the presumption that he knew her. That intimacy Ada had thought only she and Camille shared.

‘Only when we’ve got a job. Which is most of the time.’

‘And I’m still not allowed to know what this job is? Other than it involves an abbey that you need a map for.’

‘No, Camille’s orders.’

‘I see. At least that hasn’t changed. She always did like to be in charge.’

‘Why, was she very different when you knew her?’

‘In a way. It doesn’t surprise me, if that’s what you mean. I could see it in her. But life was different then. She had her parents. We didn’t have to make these sorts of choices about who we were going to be.’