Caitlin went on. ‘But there’s no point shitting you, is there? You know the deal already. What I am, what I was doing.’

‘Old,’ shrugged Monique.

‘Bottom line is, I need you. I’m fucked up with this… tumour. The effects come and go. I’m fine right now but I still feel like shit. And I can never tell when I’m gonna lose it – fall on my ass, pass out, who knows what? So I could give you a line about how I’m responsible for you, how I got you into this mess and how honour demands I get us both out. But fact is, I’m fucked and I need your help. I have nobody else in what’s left of the world.’

They came around a bend in the street and spied a minibus up ahead. A man was loading his family into it, with about a month’s worth of supplies by the look of all the boxes and bags of food he was manhandling into the cabin. Monique caught Caitlin scoping them out and was about to object but the assassin smiled crookedly.

‘Don’t worry. I’m not about to wax a bunch of kids and steal their ride. You have to have more faith in me. I know it’s hard for you to believe, but people like that – normal, decent folks – in the end they were my mission. Protecting them.’

Monique examined her with wry detachment, almost tripping on a dead pigeon from not watching her footing. ‘Not them so much, Caitlin,’ she replied. ‘They are French, and you are not. I know enough now about your world to understand what that means. You told me about Noisy-le-Sec, remember. And this Echelon is no secret. There have been books and news stories written, and a French government investigation. I read about it in Le Monde. Not so secret, no? It is a well-documented conspiracy of the English-speaking world.’

Caitlin smiled. ‘There are knowns and there are unknowns, Monique. But you’re right in one sense. Sometimes governments, agencies, whatever, they might set themselves against each other, but I’m talking about the wider picture. People like that…’ – she nodded ahead at the family now loading the last of their number into the bus – ‘people who want nothing more than to go about their own business, raising their kids, keeping them safe, giving them whatever chances they can to do better. The world they want to make is worth fighting for. They are worth defending.’

‘Against my boyfriend?’ asked Monique, giving full vent to her sarcasm.

Caitlin stopped and held her gaze. ‘Yes.’

‘Merde dors…’

They started moving again. Monique’s shoulders had hunched forward and she was holding her arms stiffly by her sides. Caitlin recognised it as one of her tells: she was furious again.

She sighed. ‘Bilal Hans Baumer,’ she said, and immediately caught Monique’s attention.

‘You know his full name?’ She looked both surprised and wary.

‘Of course I know his name, darlin’. He was my target.’ She dropped into her best Schwarzenegger. ‘I haaf extensiff files.’

The French girl didn’t get the reference. Caitlin pushed on regardless.

‘Bilal Hans Baumer. Born 5 May, 1974 in Hamburg, Germany. Parents, separated. A German auto mechanic, Hans Baumer, and Turkish mother, Fabia Shah. His father named him Wilhelm, but Hans was a drinker and abandoned the family after losing his job in 1978. His mother was a reformist Muslim. Her brother Abu came to act as a surrogate father for the boy after Hans took off. Abu had always called him Bilal instead of Wilhelm. The name stuck – don’t stop walking. Come on, we’ve got a lot of ground to cover.’

Monique had come to a halt just metres from the back of the minibus. The father, who’d been about to climb into the driver’s seat, caught her eye. He looked guilty, as though she had found him out doing something shameful. Monique favoured him with a shaky smile, and he nodded, taking in their backpacks and the appearance of flight that hung about them.

‘Bonjour,’ said Caitlin as they passed. ‘Bon chance.’

‘Bon chance, mademoiselles,’ he nodded back, before climbing in and closing the door with a slam. Caitlin scanned the back of the van, thinking of asking for a lift, but it was crammed full with children, adults, boxes, suitcases and food.

‘Why are you telling me this?’ asked Monique as the minibus pulled away.

Caitlin kept walking. ‘Through his uncle, Abu, Bilal came to meet other lost boys, most of them the products of failed unions between German men and migrant women. His mother stills lives in Neukцlln in the council flat where he grew up. She works for the Berlin City Council records department. She is inordinately proud of his achievements. He is one of the few young men in the neighbourhood to finish school, let alone university. He has a real job, and would have represented Germany in volleyball at the Athens Olympics.’

A few people were beginning to show up on the streets now, some of them also dressed for hiking. Another family emerged from an apartment block just across the street. The children were crying, complaining about the way their eyes stung and how it hurt to breathe. A young man rode past on a bicycle, wearing goggles and a painter’s disposable mask. He rang his bell as he passed them, fluttering his eyebrows. It drew a brief smile from Caitlin, made her feel a little better. But still she continued.

‘Bilal is tall and rangy with light olive skin and thick, wiry hair, coloured darker, almost caramel blonde. He has wide shoulders, long well-muscled arms and legs. No fat. Deep brown eyes, so brown they almost appear black from more than a few feet away. A ready smile that seems to spark off a high level of nervous energy. He rarely sits still for more than a moment and is given to little jumps and skips when he’s excited. He talks with his hands.’

Monique was staring at her now, almost walking into a pole at one point. Her eyes were wide, and anxious. As far as she knew Caitlin had never met Bilal, of course, but she had just described him perfectly.

‘Uncle Abu encouraged him to remain in school and proceed to university while many of the young men around him had simply gone onto welfare. Abu funded the boy’s education and supported his mother. As Bilal Baumer, he studied the German equivalent of sports science and became a qualified personal-fitness instructor, first working for a health insurance company, providing physiotherapy and rehab training for older clients, and later moving to a gym, where he proved very popular with the female clientele. I believe that is how you met, in fact, when he took you for a complimentary training session at a women-only gym in Berlin. When you were in the city eight months ago.’

Monique now looked physically ill, but Caitlin gave her no respite.

‘Bilal took up beach volleyball after a trip to Sardinia in 1995 and became a German regional champion with his partner Jurgen Mьller. Their run to the Olympics was cut short by Mьller’s acceptance into the Deutsche Marine.’

They had stopped walking again, and now stood on the edge of the gutter while Caitlin quickly checked up and down the street for any signs that they were being followed. It seemed clear. She spoke without emotion, simply recalling the facts from the dossier she had committed to memory as soon as her case controller had handed her the file on the al-Qaeda recruiter known as al Banna.