It is dawn on a June morning in Siberia in 1908. The sky is cloudless, but even in summer this part of Russia the cold at dawn takes your breath away. Fur-clad nomads are beginning to herd their sheep and goats towards lush grazing on the banks of the river-one of the thousands that drift sluggishly across Siberia's vast featureless wilderness towards the Arctic Ocean. Swans glide in the dark shallows of the river. A phalanx of ducks spears into a nearby swamp and sends up a black cloud of ferocious mosquitoes; they settle again around a herd of reindeer browsing on the river bank. Here where the tiaga, the forbidding Siberia forest, obscures the sun, the cold is a sharp as the flint in the river bed. It cuts the farmer who has just emerged from his log cabin. He halts on the steps to decide whether this first task of the day will be to mend the plough that was broken yesterday when he dug too deep and reached permanently frozen ground, or whether he will hunt for rabbit for the evening meal; instead he lights his pipe. Two families of nomads are still asleep in their tents, the air strong with the scent of wet dog as the ice melts on their furs. At a trading post, trappers squabble over the price of ermine and sable pelts. On the edge of the settlement a tramp with pots and pans jingling on his back sets off on his day's journey  to the nearest village, twenty miles away. At the edge of the village, a boatman pushes off from the river bank for his first crossing of the day, the crescent-shaped hull of his boat overloaded with squawking chickens, snarling dogs and silent peasants.

Without warning there is a blinding blue flash in the sky, followed by a roar and a searing blast of heat; there is a thunderous clap, the ground shudders, and this air is filled with fire, black smoke and debris.

The boat disintegrates, hurling men and animals into the freezing river. The farmer's shirt is scorched off his back; the tramp is blown off his feet, his ports and pans scattering like shrapnel. One of the trappers standing in the doorway of the trading post is knocked unconscious, overcome by the searing heat; the tents of the nomads are torn loose, the men and dogs inside being rolled over the ground like leaves in a gale. All that remain of the reindeer are charred carcasses. The forest has been turning into a crackling inferno, and a black fireball rises into the air.