The aim was to quarantine New York and Long Island in such a way that the diseased and the healthy would all be treated fairly. They were working flat out to achieve that, and at first the mood had been optimistic. New York seemed prepared. After the first attack on the World Trade Center in 1993, the mayor at the time had created the Office of Emergency Management, OEM, to tackle any future crisis. At the end of the nineties, it had carried out the biggest emergency drill in the city's history by simulating a chemical-weapons attack, calling on over six hundred police, fire-fighters and FBI agents to 'save' New York. The drill had gone without a hitch, and the Senate had authorised generous additional funding. Suddenly the OEM had found itself the recipient of fifteen million dollars to spend on a bombproof armoured command centre with its own air supply, big enough to house forty highly qualified workers, who were waiting in anticipation of Doomsday. It was built on the twenty-third storey of the World Trade Center shortly before 11 September 2001. Now, the OEM was still rebuilding itself, and it certainly wasn't capable of dealing with the crisis. People were falling ill and dying too fast for anyone to help.

The jeep swerved to avoid dead bodies and approached the junction with 14th Street. Cars sped by, honking frantically. People were trying to leave the city, but they wouldn't get far: the roads were closed. So far the army had only brought Brooklyn and parts of Manhattan under any kind of control, but at least no one was able to leave Greater New York without authorisation.

They drove on, passing military blockades on either side. Hundreds of soldiers were sweeping the city like alien invaders, faceless behind their gas-masks, lumbering and misshapen in their bright-yellow NBC suits. The OEM team was out in force as well. Across the city, bodies were being loaded on to stretchers and taken away in military jeeps or ambulances. Crashed and abandoned vehicles blocked the roads, cutting off access to parts of the city. The perpetual roar of helicopters echoed through the canyons of the streets.

Peak's driver trundled a few hundred metres along the sidewalk and stopped outside Bellevue Hospital Center on the hanks of the East River, where the provisional command centre was housed. Peak hurried inside. The foyer was crowded with people. Panic-stricken eyes turned towards him, and he quickened his pace. Photographs of missing people were thrust in his direction, and shouts and cries besieged him. Flanked by two soldiers, he crossed into the secure area and marched towards the hospital's IT centre. A tap-proof satellite link connected him to Chateau Whistler. After a few minutes, he had Li on the line.

'We need an antitoxin, and we need it now.'

'Nanaimo is on the case.'

'We can't wait that long. New York is out of our control. I've seen the plans for the drains, and you can forget about pumping the city dry. You may as well talk about draining the Potomac.'

'Do you have sufficient medical supplies?'

'We can't treat anyone! We don't know how to help them. All we can do is give them immuno-modulating medication and pray for the algae to die.'

'Listen, Sal,' said Li, 'we're not going to let this beat us. We're almost a hundred per cent certain that the toxins can't be transmitted from person to person. There's almost no risk of contagion from the bodies. We've got no choice but to wipe the bugs out of the system. We'll douse them in chemicals, burn them, plead with them – whatever it takes.'

'Well, go ahead,' said Peak, 'but it won't do any good. OK, the wind will probably blow away the toxic cloud, but as for the algae… Don't you realise that every single person in this city will have helped themselves to water? They'll have showered, done the dishes, had a drink, topped up the goldfish bowl and God knows what else. People have been washing their cars. The fire service has been putting out fires. This whole city is covered with algae. They're contaminating the buildings, swarming through the air vents and the air-conditioning. Even if we've seen the end of the crabs, I don't know how we could ever stop the algae reproducing.' He struggled for breath. 'I mean, Christ, Jude, there are six thousand hospitals in America, and less than a quarter are prepared for a crisis like this. How are we ever going to isolate so many people and get them treated before it's too late? The Bellevue can't cope, and it's huge.'

Li was silent for moment. Then she said, 'OK. You know what you have to do. Turn Greater New York into a prison. Don't let anyone in or out.'

'But they'll die if they stay here. We won't he able to help them.'

'I know. It's terrible. But we've got to think about everyone else. From now on, I want New York to be an island.'

'How am I supposed to do that?' Peak sounded desperate. 'The East River flows inland.'

'We'll think of something. But in the meantime…'

Peak didn't hear the explosion: he felt it. The ground shook beneath his feet. There was a muffled rumble and Manhattan trembled in the shock waves, as though there'd been an earthquake.

'Something's exploded,' said Peak.

'Find out what it is. I'll expect your report in ten minutes.'

Peak ran to the window, but there was no sign of trouble. He signalled to his men, and hurried out of the room, back along the corridor and towards the rear of the hospital, where there was a view across Franklin Drive and the East River towards Brooklyn and Queens.

He looked left, following the river upstream.

People were running towards the hospital. About a kilometre away he saw an enormous mushroom rising in the sky. It was hovering above the site of the United Nations headquarters. At first Peak was afraid that the building had exploded. Then he realised that the source of the cloud was closer than he'd thought.

It was billowing from the entrance to the Queens Midtown Tunnel, which crossed beneath the East River and connected Manhattan to the opposite bank.

The tunnel was on fire.

Peak thought of all the cars that littered the city – the pile-ups on the roads, the vehicles that had collided with shop-fronts or streetlights. He thought of all the drivers who'd collapsed at the wheel. He didn't need to be told what had happened in that tunnel, and it couldn't have happened at a worse time.

They ran back into the building, through the foyer, heading for the jeep, their movements hampered by the protective clothing, but somehow Peak managed to swing himself over the side of the vehicle and they accelerated away.

Three storeys above them, Bo Henson, the deliveryman who'd done battle with FedEx, passed away.

The Hoopers had already been dead for hours.

VANCOUVER ISLAND, Canada

'So why Whistler? What are you doing there?'

It was supposed to be an excursion back to normality, but so far it was nothing of the kind. For the first time in days Anawak was sitting in Davie's Whaling Station, talking to Shoemaker and Delaware, who were draining a couple of cans of Heineken in his honour. Davie had closed the Station until further notice. His land-based expeditions had failed to catch on. The idea of watching animals held no appeal. If the whales had turned against humanity, who could trust bears? Besides, there was no telling what the Pacific might spring on them, now that Europe had been flattened by waves. Most tourists had abandoned the island already. As Davie's manager, Shoemaker was taking care of the Station on his own, trying to keep the place afloat by calling in old debts. 'I'd give anything to know what you're up to,' he repeated.

Anawak shook his head. 'It's no use bugging me, Tom. I promised to keep my mouth shut. Can't we talk about something else?'