‘Well most people think there’s nothing in them, hence blanks,’ said Zac. ‘But there’s still a charge in the round. It has gunpowder and what have you, but instead of a bullet, there’s paper wadding. Quality weapons don’t like to shoot paper.’

‘So it’s not really a blank at all?’ asked de Payns.

‘No, it’s more like a fraud. Everything looks normal on this side’—he held a flat hand to his right—‘but what comes out over here isn’t what you thought you put in.’

De Payns stood, his mind spinning. ‘Thanks Zac.’

The team returned to the SCIF at 1 p.m. and de Payns focused on Ackermann. ‘Josef, you said that a large-scale attack with weaponised clostridium would require too much of the material to be added to a city water supply, and there are too many filters and treatments at a water plant?’

‘Yes, around seven stages. Water engineering is pretty advanced.’

‘What’s the final stage?’

Josef Ackermann rolled forward and looked at his files. ‘It’s one of the chemical treatments. Chlorine or, in the new plants, chloramine.’

‘How do they dispense the chlorine?’

Ackermann held up a colour brochure showing large blue plastic barrels. ‘They’re like a cartridge that slots into the pipe at the very end of the process,’ said Ackermann. ‘The water is treated by the chlorine, and when it passes out the other side the bugs that weren’t killed by the previous six stages are now dead.’

De Payns thought about what Zac had said about blanks being better described as frauds. ‘What if there’s no chlorine in the canisters?’

Ackermann seemed confused. ‘Well, the water wouldn’t have that final treatment.’

‘Okay,’ said de Payns. ‘What further treatment is there after the chlorine?’

‘None,’ said Ackermann. ‘Unless you have a filter under your kitchen sink.’

‘Okay—and this is just a theory—what would happen if you took the chlorine out of the canisters and filled them with weaponised clostridium?’

Marie Lafont screwed up her face. ‘That’s just gross.’

Ackermann gulped.

Briffaut turned to Shrek. ‘Those samples you brought back from Palermo? The clostridium was on chlorine.’

‘Yes, it was,’ said Shrek, eyes focusing.

‘What if they were bringing in genuine water treatment canisters that were filled with chlorine, then emptying them and refilling them with the clostridium?’

‘That would mean water treatment canisters arriving at Porto di Palermo, having their contents swapped, and leaving from there as well,’ said Briffaut. ‘Hand it to the DR. They can do this quicker than anyone. Chlorine is a reportable substance. Let’s find out who was bringing it in and shipping it out.’

Marie Lafont picked up one of the conference phones in the middle of the table, and turned away.