I would have resented this more if I hadn’t been glad to retreat, having seen how we appeared to have descended considerably deeper than I’d thought – so deep that the sliver of daylight between the walls far overhead could have been just an illusion, while the blackness that seemed to be seeping out of the walls was the truth. As I regained my seat and fastened my safety belt, I grasped that Bella wanted to leave as soon as she finished her task, and then I realised she hadn’t warned me against speaking the name for my own protection. She was concerned if not afraid for herself.

The insistent repetition of the name had started to acquire a depth that made my head feel hollow, and I wondered whether Bella was hearing the voice too. She took an empty screw-topped jar out of her bag, which she left on the seat as she emerged from the car. Her supple movement looked resolute, more consciously performed than her habitual grace. “Leave it, Patrick,” she said when I made to shut her door. “And leave the engine on.”

I was disconcerted to see her following the headlamp beams to the river. No doubt they illuminated her route, but did she prefer to stay clear of the dark? The ritualistic repetition in my head left very little room for thoughts, and I didn’t know how it might be affecting Bella. Her behaviour made the light feel discouragingly vulnerable, a token glow in danger of being crushed by the weight of the dark. I watched her reach the riverbank, where she unscrewed the lid and bent to scoop up mud with the jar. She replaced the lid and screwed it tight before rinsing both her hand and the jar in the river. Straightening up, she gazed about with a triumphant look, and then stooped to drink a handful of water.

I took it for a gesture of defiance until I saw it give her power. As she rose to her full height she appeared to gain stature, growing taller than I’d ever seen her. She wasn’t just catching the headlamp beams; she appeared to be absorbing their light, shining as luminous as a denizen of utter darkness. She had her back to me, and I glimpsed movement at her shoulders. Beneath the fabric of her T-shirt, some kind of growth was taking place in the hollows I’d felt there, perhaps a reversion to her true shape. For a moment I expected to see wings unfurl, or the emergence of some appendage still less common. Perhaps realising that the transformation would delay and hinder us, she turned back to the car.