‘Yeah,’ Foster said. ‘We took a stroll after the meal, just in time for some guy to get a home-made explosive over the gates.’

‘Jesus!’ Keller sighed. ‘What did you do?’

‘I did what I would have done if I was on duty,’ Foster said. ‘I reacted by smothering the client. I took the brunt of the explosion on my arm.’

‘That’s so brave,’ Keller said. ‘How was the client?’

‘Not a scratch.’

Keller turned on her side and twisted around him like a question mark.

‘You should be so proud of what you did,’ she told him.

‘Well, I’m not.’

Keller scanned Foster’s face in the half light, trying to make sense of him.

‘Why not?’

Foster took a breath and watched the planes travelling across the sky into Heathrow, but before he could explain, Kirsten Keller’s mobile phone began to ring. The phone never rings at 4 a.m. with anything but bad news, and twenty seconds later Keller gasped and dropped the phone.

‘Jesus Christ!’ she breathed, wide-eyed and gulping for air. ‘Maria’s dead.’

CHAPTER 11

LONDON WAS STILL waking up as Foster drove the Range Rover back towards Wimbledon, with Kirsten silent and ashen-faced in the passenger seat. The low sun glinted off the sides of the glass buildings flanking the Thames, and every second car was a cab. The house that Keller had hired with Rosario was cordoned off and bathed in blue police lights.

‘Jesus Christ!’ Keller breathed as they drove into the street. A uniformed officer recognised her and waved the Range Rover through. The house was halfway along a poplar-lined street, a spacious old red-brick pile surrounded by a hundred other spacious old red-brick piles. The photographers were gathering on the street outside, and the residents had come out to see what was happening.

‘Are you sure you want to do this?’ Foster asked as they pulled up outside. Keller shook her head, barely lifting her eyes from the footwell.

‘I’m not sure about anything right now.’

‘You want to stay in the car?’

‘No,’ she said hesitantly. ‘I want to find out what happened to Maria.’

Foster took a breath and turned off the engine.

‘I’m not sure they’ll tell us that.’

But Keller was already opening the passenger door, which was a mistake, because she was walking straight into a crowd of people. Foster clicked open his seatbelt and rolled out of the driver’s door, so that by the time she’d rounded the car, he was by her side.

‘What’s happened, Kirsten?’ the reporters called. ‘Are you going to make a statement?’

A police officer standing guard on the door ushered them both inside, and then closed the door quickly behind them as the cameras started clicking. The entrance lobby was impressive, with thick walls and a corniced ceiling as sharp and flat as a billiard table. The place had been modernised, stripped back to white walls and oak floors.