Smoke leaked from the chimney. A light flickered in the window, but the panes were smeared with grime and impossible to see through. I circled around to the front door and stamped the snow off my boots. I breathed deeply, sending a column of silent white mist into the air. Since I’d fled the burning cottage in Donegal, all roads had led me here. Led me home.

Whatever happened next, I knew Rachel would at least want to know how her father had really died. In Tel Aviv I’d braced myself to be confronted, hoping all the while to be forgiven. I’d thought I’d been prepared. But as soon as I’d stepped into her office, I’d been swamped with uncertainty. I still was, but with this difference: I no longer knew which of us was guilty, or of what. I thought that I had come to assuage her. But I hadn’t. I’d come to accuse her. What followed might lead to revenge. Or atonement. Either way, I told myself, I’d be ready.

Midnight in Arkhangel and all was quiet.

I raised my fist to strike the door, but as I did so I saw that it was already open. I pushed it gently, and stepped through the looking glass.

32

Rachel was facing away from me, sitting on the floor in the middle of the room, knees drawn up to her chin, arms locked around her shins. Her hair hung long, falling down the back of her tunic in a jumble of black tresses.

Three candles – arranged neatly in a line – burned on an old dresser pushed up against the far wall. Wax spilled on to the bare floorboards. The remains of a fire glowed in the stove. I closed the cabin door quietly and stood still, letting my eyes adjust. The ceiling was fouled with lamp soot, the walls covered with crazy patterns scored into them by years of decay.

Before I could speak, she said: ‘Ner tamid.’

She turned and looked hopefully at me over her shoulder. She was both Rachel and a stranger – familiar and yet disarmingly different. Her face was set with worry; a hard journey etched in her eyes.

‘I’m sorry,’ I said. ‘I don’t understand.’

‘Eternal light,’ she replied, pointing to the taller candle in the middle. ‘God’s gift to us who live in darkness.’

I took a step closer. I looked at her, at the room. Light pooled above the candles. The marks that at first had looked like random patterns in the cracked wooden panels took shape. The whole back wall was covered in an organized explosion of mathematical calculations. Dead centre, repeated in dozens of permutations, the serial number of the hundred-dollar bill: 73939133.