‘As you can imagine, it is not as simple as that.’

‘And this one’s repairing itself because?’

‘Because you are here, Mary. The land responds according to our natures. Some people are weak in magic. Others are strong, like you. You can drink deeply from the well beneath us. The castle was never very big, and I lost heart, so it fell into ruin. Now, it is responding to your presence, and grows once again.’

‘Me? What did I do?’

‘You do not have to do anything. You just have to be.’ Crows tapped his foot on the boards, and they sounded hollowly back.

Mary looked around her with wonder. ‘This grew, out of nothing?’

‘Again, not out of nothing. Out of the ground. It rises and falls with the power of the men or women under its roof.’

She pressed her hand against the wall, where the individual stones fitted with each other in blocks and courses, like a gigantic jigsaw. ‘That is still fucking nuts. So how do you find these lines of energy?’

‘You search for them. Tease them out. Remember how I told you that maps were powerful things? This is why: if you have a map, you can start to find the lines. Once you have drawn the lines, you can find where they cross. Where they cross is where castles rise. And sometimes, you can, if you are clever and you have more complete maps than anyone else, you can find a place that no one else knows of.’

‘Do you?’ she asked.

‘Do I what?’

‘Have maps?’

Crows pursed his lips. ‘I might.’

‘Can I see them?’

‘Mary,’ he said. ‘They are fragile, and very precious. They are not objects to be idly toyed with. But perhaps … yes. You must start a map of your own, and mark everything you know of so far on to it. Come, and eat, and then while it is still light, we can make a start.’

Crows wasn’t much of a cook, Mary decided, not that she could do better with the ingredients to hand. There was steamed fish – bony and tasting oddly of weeds – and boiled grain that was a step firmer than porridge. He thought it was fine: he extracted every last morsel of grey flesh from the skeleton, scooping out the difficult to reach bits near the head with one of his long fingers, and sucking the juices from the tail, all the while using the same fingers to cup small balls of grain and feed them past his white teeth.

If she didn’t eat, she’d be too weak to walk to all the places that Crows thought it necessary to take her to, and too weak to weave fog from the air she breathed and darkness from the shadows she cast.