FOSTER SLEPT FOR five straight hours that night, outside Kirsten Keller’s room at the Shangri-La, waking with the light pouring through the unshaded glass. The unbroken half of his body pulled the rest of him from the sofa, and fierce pain instantly spread across his ribs. He spent the day with a brooding sense that trouble was coming, but it never did. In the evening, he sat with Keller and watched the sun setting behind St Paul’s Cathedral, and the last of the river traffic crossing the muddy Thames, and the London Eye slowly turning like the mechanism of a giant clock. Days passed with the same aching sense of dread, but Keller’s matches came and went, and she won them all, and nobody came out of the shadows.

Foster woke to grey skies on Thursday morning, knowing that Keller was facing Marta Basilia in the semi-finals, and sensing that if her attacker was going to strike, he would have to do it soon. Foster’s body still ached, so he found a tumbler and filled it with water, then gulped down four large codeine tablets. He woke Keller an hour later when the sky had turned to a warm summer blue. She showered and dressed and they ate breakfast in the Shangri-La, before heading across London listening to the Rolling Stones, Jagger’s mournful voice setting a tone for the journey.

‘What happens if I see him?’ Keller asked. ‘You know, staring out from the crowd?’

‘Let me know,’ Foster said simply. ‘And I’ll come and get you.’

She stared at him.

‘On the court? Seriously?’

‘Yes, seriously,’ Foster said.

Keller looked at him for a moment, studying his face as he watched the road ahead. He sensed her stare and glanced across at her.

‘What?’

‘Nothing.’

She sat back in her seat and smiled, and Foster drove on until they reached Wimbledon. Keller settled into her pre-match routine and Foster melted into the background, watching everything and trusting no one. He saw the crowds swell on Centre Court, slowly blooming and spreading over the green plastic seats like spores on a Petri dish. His skilled eyes swept through the mass of people, watching for anything unusual. In the end he saw nothing but thousands of excited fans gorging on strawberries and protecting themselves from the midday sun. By the time Keller reached the court, the atmosphere was electric.

Keller lost the first set 6–0, unable to find a rhythm. Her eyes flicked constantly from Basilia to the grandstand and back again, her mind distracted by the baying crowd and its lurking danger. Foster could almost hear her nerves jangling as she sat dejectedly in an olive-green chair with her head under her towel.

‘How’s it looking outside?’ Foster asked, as Tom Abbot appeared by his side.

‘Nothing doing. It’s all quiet.’

‘Okay.’

‘Think she can get back into it?’ Abbot said.

‘She will,’ Foster said. ‘She’s a fighter.’