“Whatever happened to Billie, maybe it was an accident. I know it would’ve been Daniel who saw an opportunity to make money from it. Not you. Or maybe she’s still alive, maybe someone’s taking care of her . . .” His eyes had flashed again to the outbuilding. “Maybe you feel trapped now, like you can’t undo it. But you can. I can help you. I love you.”

She had begun to shiver violently. It had seemed to last forever: Nathalie standing there, trembling, her chest rising and falling hard.

When she’d finally spoken, it had been in a low, alien voice. “How could you think that about me?”

“That’s what I’m trying to say. I know Daniel must be behind it—”

Her volume soared. “How the fuck can you think that about either of us? He’s your friend, and I . . . I . . .”

“He’s not my friend.”

That had reduced her to silence. Paul instantly knew he’d said too much. Nathalie had stared at him again and he’d taken deep breaths, trying to rein himself in, to remember his training and how much was at stake.

“Who the hell are you?” she’d asked.

The question had seemed so inevitable it was like déjà vu, like they’d already had this conversation in multiple parallel existences. It was always bound to come down to this.

Stay in character at all times. Talk, walk, feel, and dream in character.

Stick to your story unless you are absolutely certain your cover has been blown.

Have explanations ready for when anybody doubts or questions you. Recite them in your head before you go to sleep, when you wake, when you shave and shower and sit on the toilet . . .

“You’re not who you say you are. Are you?”

“Of course I am, baby—”

“Don’t call me baby!” She’d thrown up her hand to ensure he didn’t move any closer. “I’m not the only one who sneaks off places.”

“What?”

Always preempt. Know where the danger is coming from even before it arrives.

But Paul had no longer been sure what he was most afraid of: losing Nathalie, or destroying the whole operation. Were they one and the same? Glover’s voice had kept coming into his head, then falling away again as soon as he’d looked at Nathalie and felt his heart wrench.

“I’ve noticed something lately,” she’d continued, her voice growing stronger, but still with a tremor. “You go off to use the phone box at the same time every week.”

He’d feigned half-amused confusion. “Do I?”

“Exactly the same time.”

He’d been spending far too much time with her. Letting her stay in his flat more often, rather than hers. Enjoying the morning warmth of her in his bed.

Giving her a chance to observe his routines.

“I’m a creature of habit.”