‘Thank you for that,’ said Costain. He held Ross. She kissed his cheek, feeling his fear. She felt only professionally satisfied that she might have saved him. She was acutely aware of the missing emotion. She felt the shock entering her and being amped up by the drugs, and she knew there’d be no happiness in the future to balance it, that there was increasingly nowhere left for her, emotionally or, she was starting to feel, physically.

*   *   *

They went to look at the victim’s body, around which a crowd was now hesitantly gathering. Costain looked through his pockets and found a phone: a brand new cheap one, the sort you could get from a market stall, with no contacts in the memory. ‘Bet he was told to ditch the old one right before tonight,’ he said, ‘so there’d be nothing to associate the corpse with Vincent.’

The concert audience was shying away from those Toffs who had stayed, some of whom had now taken their masks off, to reveal students and a disparate range of mainstream London faces. Some of this lot would be coming forward in a moment to say that a Toff had done this. ‘We need to find out if we can pin the purchase of that ticket on Vincent,’ said Sefton, sounding as if he knew how little a thing that would be.

‘Already put in the request,’ said Ross, looking up from her phone. With shaking hands, she took her rough books and portable Ops Board from her bag. She sat down on the steps and drew some satisfyingly certain lines across the Ops Board, the only control over anything she could have now. ‘It refuses to kill women,’ she said. ‘So Mary Arthur is safe. If only we bloody knew how to find her.’

*   *   *

They waited until the paramedics had arrived to deal with the remains of Challoner. Ross felt gutted at the idea of putting a body, a crime scene and evidence into the hands of people other than police and associated specialists. The medics looked surprised that coppers were actually here. One looked pleased, the other disgusted.

What could they do? What was left?