"I don't wish to state the obvious, but if that door comes down, it will take more than a shower to decontaminate us," Moulding said in a quiet voice that crackled with tension.

McShay came out of his stupor in a flash; the thought that a security door designed to survive a direct nuclear strike might ever be breached was so impossible, his mind hadn't leapt to consider the consequences of what was happening.

"Everybody fall back!" he yelled. "We need to seal this area off-"

The next second the door exploded outwards. McShay had one brief instant when he glimpsed the shape that surged through and then the gunfire erupted in a storm of light and noise, and a second after that a wave of soft white light came rushing from the reactor core towards them all.

The first person to see what had happened to Dounreay Nuclear Power Station was a farmer trundling along the coast road in his tractor. The sight was so bizarre he had to pull over to the side to check it wasn't some illusion caused by the sea haze. The familiar modernist buildings had been lost behind an impenetrable wall of vegetation; mature trees sprouted through the concrete and tarmac, ivy swathed the perimeter fences and buildings, dog roses and clematis clambered up the side of the administration block, cars were lost beneath creepers; all around squirrels, rabbits and birds skittered through the greenery. And if anyone had decided, for whatever reason, to check for radiation, they would have found none, not even in what had been the reactor core. Nor would they have found any sign of human life.

May 2, 8 p.m.; News International: Wapping, London:

"There's no point in us being here." The accent was pure Mockney, hiding something from the Home Counties. Lucy Manning repeatedly punched the lift button, then shifted from foot to foot with irritation as she watched the lighted numbers' soporific descent. She was in her twenties, dyed-blonde hair framing a face that had the cold hardness of a frontline soldier.