The idea of weaponizing such a delightfully deadly substance was hardly original, of course. But no one had ever done so before – for a very simple reason. Delivery was nearly impossible. The toxin must be ingested or inhaled or enter the body through mucous membranes or open wounds. Contact with skin alone is not enough. Since it is very difficult to deliver a large amount of aerosol toxin, that meant an attack would have to be via food or water.

But salt, heat, alkaline substances and oxygen can kill the bacteria. So will chlorine, which is added to New York City’s water supply, along with the anti-tooth-cavity additive fluoride, orthophosphate to counterbalance lead contamination and hydroxide to increase the alkalinity of the supply.

Billy, however, had learned to grow a concentrated form of botulinum that was resistant to chlorine. Yes, some of the toxin he injected into the water supply would be destroyed, or its deadly effects dimmed, but the estimate was that enough would survive and be carried to households throughout Midtown and lower Manhattan and much of Queens. The death toll would probably be four thousand or so; the sick and severely injured would be many times that.

One group would be particularly hard hit: children. Infant botulism poisoning occurred with some frequency (often children younger than twelve months who’d eaten honey in which spores naturally resided). Billy had considered their deaths and he didn’t feel troubled by them. This was a war, after all. Sacrifices had to be made.

The city would react quickly, of course, with the Health Department and Homeland Security racing to find the source of the illness. There’d be some delay as officials thought chemical nerve agents – the symptoms are similar – and with some luck medical workers would start injecting atropine and pralidoxime, which actually increase botulism’s lethal strength. Some would diagnose myasthenia gravis. But then would come the serum and stool tests and finally mass spectrometry would confirm what the disease truly was.

By then, of course, the damage would be done.

A secondary consequence, which would cause even more extensive, if less lethal, damage was also predicted by the Modification: The city would soon find the source of the toxin but wouldn’t know how far-flung the poisoning was. Was the Bronx in danger next? New Jersey or Connecticut?

The only thing the authorities could do – the utterly incompetent city, state and federal governments – was shut down the entire water system. New York City, not a drop to drink, not a drop to carry away sewage. Or clean. Or generate electricity (most of the city’s power came from electric generator plants whose turbines used steam). The East River and the Hudson would become a Ganges, a source of bathing, waste and drinking water … and disease.

A plague, not a flood, would destroy the city.