Capabilities she would soon get to display, as the receiver in Dempsey’s right ear whistled into life.

‘All birds are perched. Over.’

Dempsey glanced towards Dai. He had no need to ask if she was ready. He lifted his hand back to his ear.

‘On my mark.’ Dempsey opened the driver’s door as he spoke. Dai did the same on the passenger’s side. ‘Let’s move.’

The entrance to the run-down tenement block was a green door that led directly onto the Chinatown section of Lafayette Street.

A busy New York thoroughfare, Lafayette was usually packed with streams of both locals and tourists. Today was no exception.

Too many potential obstacles here, and no way to remove them, Dempsey had concluded. An operational nightmare.

Luckily for Dempsey, those inside the building faced problems of their own. The tenement’s blueprints revealed a bottleneck in the corridor that led towards Lafayette.

The slightest panic and that exit becomes a death trap, Dempsey had observed. No way they’d risk that. They must have another route out.

With Lafayette ruled out, there was only one viable way in and out of the building: the adjacent, much quieter Walker Street, by way of the tenement’s fire escape.

Sharpshooters from the NYPD’s SWAT unit were already in place, dotted high on both sides of Lafayette and Walker. All carefully chosen locations that offered clear, downward lines of sight into the target block. They provided a lethal blanket of firepower, ready to extinguish anything that emerged.

The ultimate insurance policy, should anything go wrong.

But still not quite enough for Dempsey. Although a SWAT team would probably be sufficient, he was taking no chances. He had placed two of his own ISB agents – both male, both Chinese – close to the green door. Inconspicuous and ready to react in an instant.

They’d be crazy to come that way, he had thought again, but there’s no accounting for bad decisions.

Dempsey and Dai passed the two covert agents at the Lafayette entrance, turned the corner into Walker Street and headed for a break in the first block of buildings. The entrance to the alleyway that contained the tenement’s fire escape.

As they approached the alley, Dempsey slowed his pace, his eyes fixed straight ahead.

Coming towards them, from the opposite direction of Walker Street, were two men.

One was larger than Dempsey; several inches taller and significantly broader across the shoulders. A naturally huge frame that had been amplified by a lifetime of physical effort. And perhaps a few chemical enhancements.

The other man was much smaller than his companion. Barely five nine. Wiry build, with a hardness that cannot be honed in any gym.

The big guy was clearly armed. He was holding a rigid three-foot-long shape, poorly concealed by a sports coat he had draped across it.

‘What part of “covert” don’t you get, Sal?’ Dempsey spoke quietly as the four came together and turned into the alley.

Without waiting for an answer, Dempsey turned his attention to two ISB agents who were already there, waiting. The final third of his Alpha team, they had reached the alleyway first and brought the unit’s number to six.