‘Stay where you are,’ Briffaut ordered as the clatter of automatic gunfire crackled on the radio, making them wince at the sudden burst in volume. The shouting between the GIGN troopers was constant and the team leader’s instructions and the feedback suggested the operators were advancing through the facility towards the rear of the building.

Shrek nudged de Payns and pointed. From the main corporate entrance of the building, a tall middle-aged man with a crown of pushed-back silver hair approached the helicopter.

‘Be nice,’ said Briffaut, as he slid out the helicopter side door and stopped the man from reaching his team.

‘Can I help you, sir?’ asked Briffaut.

‘Thorens,’ said the tall man, holding out his hand. ‘Jean-Pierre Thorens. I’m the CEO.’

‘Dominic,’ said Briffaut, taking the proffered hand. ‘We spoke earlier.’

‘What should I do with my employees?’ asked Thorens. ‘They’re frightened.’

‘What did GIGN say?’ replied Briffaut.

‘They charged straight through, told us to stay in the foyer, but it’s dangerous—we can hear the gunfire, it’s very close.’

De Payns looked at the glassed-in entrance—civilians milled around wide-eyed, the occasional one making a break for the car park.

‘What’s going on in there?’ asked Briffaut.

Thorens explained that inside the loading bay was a long, open area where five different stages of filtration and water treatment took place. A gantry crane ran the length of the building and the GIGN troopers were fighting their way towards the two massive steel sliding doors at the end of the facility, where the security area started.

‘That’s where the Rotterdam Associates people were,’ said Thorens. ‘They were working on the final filtration system, where the water is cleansed by chloramine before it goes into Paris’s water pipes.’

‘They’re behind those security doors?’ asked Briffaut. ‘The Rotterdam engineers are in the water system?’

‘Well, yes,’ said Thorens. ‘They had their passports, which were all cleared by our security check. I don’t know how your guys will get through those doors—I believe they’re bomb-proof.’

What sounded like a grenade barked in their earpieces. De Payns wasn’t too concerned about those security doors—the GIGN trained in this sort of critical infrastructure and they had master keys and manual override codes that the CEOs of these places might not even be aware of. He was more worried about bullets going through the epsilon toxin canisters or being spilled deliberately into the water system, even as the GIGN operatives approached.

De Payns turned back to the building itself, where the sounds of a gun battle were pushing crowds of employees out of the main corporate lobby and into the parking area. Others clustered in groups inside the foyer. Whichever way they went, they were sitting ducks for one of the gunmen, and de Payns didn’t like it.

He turned to Briffaut. ‘Some of those folks need a hand.’