Ujurak watched curiously as Ed opened the square thing and took out a container about the size of a fir cone. A long spike stuck out of the top. Ed stuck the spike into the space between the door and the wall, and when he swung the door a moment later, the squeak was gone.

‘Thanks, Ed,’ Janet said. ‘I –’ She broke off, glancing at Ujurak, and then went on, ‘Ed, just give me that can for a minute, please.’

Looking puzzled, Ed handed the container over. Janet held the spike above Ujurak’s empty soup bowl, and a few drops of a sticky black substance dripped out of it.

‘Thanks, Ed,’ Janet said, handing the container back.

Ed still looked confused. ‘See you around, Janet,’ he said, and went out.

‘Now then, honey, look at this.’ Janet held the bowl out to Ujurak.

Ujurak took a deep sniff of the black liquid and reared back, staring up, stunned, at Janet. That stuff smells like a BlackPath!

‘That’s oil,’ Janet told him.

Ujurak bent over the bowl again. So that’s what all the fuss was about, back in Arctic Village! Tentatively he reached out and stuck the end of one finger into the oil, then touched his finger to his lips to taste it.

‘No!’ Janet exclaimed. She pulled his hand away and wiped his fingers and his mouth with soft paper. ‘It’s not good to eat,’ she explained, taking the bowl away. ‘It’s poisonous.’

Horrified, Ujurak stared at her.

‘Then why don’t they leave it in the ground?’

The nurse shook her head slightly, as if she couldn’t believe he’d asked that. ‘It’s too useful, honey,’ she explained. ‘We couldn’t go anywhere in trains or boats or planes, or have heat and light in our houses, if we didn’t have oil.’ She smiled. ‘And it’s great for getting rid of the squeaks in doors.’

‘But there must be something you could use that isn’t poisonous,’ Ujurak protested.

‘No, it’s too late,’ Janet replied. ‘Whole towns are built on this stuff, and on the business of getting it out of the ground. Come here and look,’ she invited.

She helped Ujurak out of bed and led him over to the window, pulling back one of the pelts that hung there so that he could look out.

Outside it was night. Ujurak stared across a wide stretch of land covered with flat-face buildings, with BlackPaths running between them. Beyond them was a river, and beyond that stood a huge tower, metal tubes extending away from it into the distance, toward the mountains. A billowing flame burned at the top of the tower, shedding sharp yellow light into the dark blue sky.

‘What happened here?’ Ujurak whispered in dismay.

‘This is the Propkin oil field,’ the nurse explained. ‘It’s how we get oil from the ground.’ Smiling, she ruffled Ujurak’s head-fur.