Sebastian does not answer, flips from his knees over to his bottom, sits there, hugging his knees, excited and happy. For a moment he has something of Charlie, full of the joy of being alive, here and now, partaking in things. The next moment his thoughts veer to dead children. His expression remains just the same. All she does is ask another question.

“Whose blood was that in the vial?” she asks.

This time he answers.

“We called her Lilith. After Adam’s first wife. A feisty little mite! Cantankerous.” He smiles with the memory, fingers his bottle. “How we scoured the world for them, in the years after we learned of their existence. All the best scientists of Europe: mounting expeditions to the farthest corners of the world. A new age of exploration. And how naïvely, how clumsily did we proceed. Walking into igloos with nothing but a scarf wrapped around our mouths, infecting whole tribes in the process. They died in droves. You see, most adults could not survive the anatomical adjustments initiated by the infection. Children though! There was our hope. And little Lilith: a lovely girl, pretty as a picture. She caught a cold, in the end, an ordinary cold! Your butler buried her, out in the woods. Your mother was heartbroken.”

The Smoke jumps out of her in a cloud of rage, is immediately smothered by some other part in her, cooler and more calculating, in need of further answers. Lilith is dead. Mowgli may still be alive. It is his blood her mother wants.

“How much do you need?” she finds herself asking.

He does not appear to have heard, sits on the ground and plays with Soot.

“Ah, there’s the rub,” he mutters at length, letting some flakes rain from his fingertips. “Two thousand two hundred cubic centimetres. It seemed little enough on the chalkboard, when I did the maths.”

Again she finds her mind reeling, starts walking abruptly, in demented circles, as though searching for sense through the geometry of movement. Her steps displace fresh motes of Soot that swirl around the hem of her dress, half harbingers, half retinue, as unsettled as she.

“We saw a row of rectangles,” she says into their dance, still pacing, not looking at him, no longer able to bear the sight of his hale face. “On your secret map of the sewers. Pools, we think. What’s in those pools?”

“Oh, it’s very clever, Miss Livia, very clever, if I say so myself. At first glance, a simple problem of filtration. Water, dirt, Soot. But the devil’s in the details!”