If she looked down into the detail at the water’s edge, she’d see terrible things, but that would be the truth too. To be part of a city was to be a cell in a bigger animal, an animal large enough to have a conversation with the sea, which the river moderated, and the sky, which the river reflected. To be part of a city was to have an index of your mortal life right in front of you: as you got older you’d start saying you remembered when it was all different around here.

She understood why those who had the Sight felt the need to hang on to the past. She herself, she realized, was trying to get back to when her dad had been alive. It was as if she was trying to begin her life again, even when everything about a city said the world went on without you.

She slowed to a stop and Costain halted too. They were halfway across the bridge. Where they stood, people had attached padlocks to the horizontal wires, usually with the names of couples on them. It was a gesture that was supposed to be about eternal love, but it had always felt a bit creepy to Ross, suggesting that locks had anything to do with love. Every month, the City of London Corporation sent people along with bolt cutters to remove them.

She understood now that she had no idea about that sort of love except as something people talked about. She’d always hoped if she ever felt like that, it’d be free of the locks she’d made for herself, of the burdens of her own quest. That it would be freeing.

She felt now how small her mission was. Just one person – her dad. She was prepared to harm Costain, to do anything, for that one tiny being. She could give all that up and choose love instead, the river seemed to be saying to her.

No, all she knew about London said the opposite: that the actions of one person could be remembered. Saving her dad was who she was. Sorry, she said now to the glory of London, I am what I am and I will do what I am going to do.

The glory of London seemed to worry in reply, to flex its river muscles anxiously, to fret about what she was going to contribute to its history tonight.

‘What are you thinking?’ asked Costain.

She turned to look at him, and was sad for him because he was with her. ‘It’s beautiful,’ she said.

*   *   *

They finally made their way to the end of the bridge, and thus to the enormous square and ugly building that had once been Bankside Power Station. ‘The Tate Modern art gallery,’ said Costain. ‘Are you sure this is the right place?’