The man was standing opposite the entrance to London Zoo, dressed in a suit and tie, the jacket buttoned up despite the steaming midday heat. His eyes were hidden behind dark glasses and he had one arm already raised in the air to hail a cab, as if he was fully expecting Mahmud to be driving round Regent’s Park’s Outer Circle immediately after prayers, as if he knew he was coming.

As if he had been waiting.

Mahmud pulled up beside him, smelling the animal stink of the zoo in summer.

‘Cash only, boss,’ Mahmud said.

The man nodded, glancing at his phone before showing it to Mahmud. On the iPhone’s screen there was a map of the City with a red marker pinpointing their destination.

Newgate Street, EC1.

Less than four miles away but it meant crossing the middle of the city in the stagnant traffic of lunch hour. Mahmud grunted his reluctant assent and watched the man slide into the back seat.

In silence they drove east through the sweltering city.

Mahmud was turning his taxi onto Newgate Street when he glanced in his rear-view mirror and saw the man removing a small leather credit-card holder. Mahmud sighed. How many times did you have to tell these stupid people?

‘It’s cash only,’ he repeated, harder this time, tugging at his polo shirt, the sweat sticking.

But the man was not getting out a credit card.

He leaned forward between the gap in the front seats and placed an old-fashioned razor blade firmly against Mahmud Irani’s left eyelid.

Mahmud drew in his breath and did not let it go.

He felt the thin cold steel of the blade’s cutting edge settle into the folds of soft flesh beneath his eyebrow. The fine layer of skin covering his eye fluttered wildly against the razor blade. Pure naked terror rose up inside him.

‘Please,’ Mahmud said. ‘Please. Just take the money. It’s under my seat.’

The man laughed.

‘I don’t want your money. Keep driving. Nice and easy now.’

Mahmud drove as if in a dream, driving with one eye squeezed closed, trying to concentrate on the road ahead with a razor blade pressed against his eyelid.

Following the man’s directions, he drove to the end of the street and then turned left onto a huge building site. It was deserted, one of those little pockets of total silence and emptiness that suddenly surprise you in the city. Another tower of glass and steel was being erected here, but there was nobody working this afternoon. They were all alone. Ahead of them was a yawning hole in the uneven ground.

‘Down there,’ the man said.

‘I have a wife and children.’

‘Too late for all that now, pal.’