Circling on snow-white wings, Ujurak let out a cry of despair. In his nightmare vision there were no more bears, no more caribou or geese or foxes, just pipes and noise and stinking air as far as he could see. The taint had even spread out to sea; black walls reared up out of the ice, spilling rubbish into the waves. There was no escape.

With a gasp, Ujurak snapped back to reality, blinking to chase away the horrible vision. His senses seemed sharper than ever. He could hear the engines pumping underground, sucking the oil from deep down, and then the oil gurgling through the pipes that carried it into the mountains.

Ice-cold terror washed over him; he could barely make his wings hold him up in the air. At last he knew the reason for his journey: the Last Great Wilderness needed his help.

Save the wild . . . he thought of Lusa’s dream. He remembered his own uneasiness along the journey, the fear of the creatures whose shape he had taken, that their world was being spoiled and poisoned, stolen from them by the flat-faces.

I’m here to fight, he vowed. Somehow I’ll find out what I have to do.

A flash of moonlight blinded him; the stars whirled around him and he realised he was falling. His wings and tail-feathers shrank away, replaced by fins, while silver scales flowed over his body. A spasm passed through him as he realised that he couldn’t breathe. Choking, he twisted in the air. The river loomed up beneath him; he hit the water and slid into it in the shape of a fish.

No . . . Ujurak thought, fighting back panic. This isn’t right! I’ve got to get back to Toklo and the others.

The fish-shape was threatening to overwhelm him, a fierce hunger driving out the memory of his friends. His mouth gaped to draw in the nourishing food that he knew the river should have offered. But there was nothing . . . nothing but tainted water and emptiness where he longed to swim upstream in the company of his kin.

I’ve got to . . . change . . . With the last scraps of his consciousness, Ujurak tried to force himself back into the shape of the owl, to soar over the oil field and locate the tall building beneath which his friends were hiding.

Flicking his tail, Ujurak swam for the riverbank. He felt himself grow bigger; legs burst from his body, and now there were four of them, ending in neat hooves. He could feel antlers sprouting from his head, and he looked down at himself to see the grey-brown pelt of a caribou.