Poor Lug, she thought. He really should have stayed back in Arborven. This whole quest has been so hard for him. She gently folded his blankets around him, tucked his mittens on tight, brushed his tousled mousy hair away from his eyes.

‘I’m sorry I made you come with us, Lug,’ she whispered to him. ‘But I don’t think I could have done it on my own. You’re like a piece of home I brought with me. And we’re here now. We did it! Please wake up so you can see . . .’

Liska had a sense of someone watching her and looked up to see Embla frowning down on them. The red-haired girl looked away and Liska blushed, worrying that she had shown too much of her vulnerable side. She was supposed to be a fierce warrior, after all.

Leaving Fishbone and Elowen to finish wrapping Lug up, she stood, wondering what she could say to this elk girl. How she could persuade her to give up the tree she had been fighting to save from freezing.

But Embla’s attention was elsewhere. She was staring out at the tundra, where the figure of Thresher could be seen in the far distance. ‘Who is that?’ she said. ‘Why do they chase you?’

‘They are our enemies,’ said Liska. ‘They want to stop us.’

‘Stop you doing what?’

Liska took a deep breath. She hadn’t planned on bargaining with someone for Nammu’s heart. She had no idea of what she would do if Embla refused to let them take it. Fight her? And then Thresher afterwards? She was too cold to even speak, let alone battle.

‘We have a tree in our city. A tree like this one.’ Liska pointed up to the branches above. ‘But it is under attack from its opposite. The shadow tree we call Bitterblight . . .’

‘You have come here for Nammu’s heart,’ said Embla. Her jaw was still set, her fist clenched around her spear. Liska sensed this wasn’t the first time she had heard such a request.

‘We thought there was nobody here.’ Elowen finished covering Lug and came to join them. ‘We thought it might even be a legend. But our city, our tree, is in danger. This was all we could think of to save it.’

‘Where are your soldiers? Your army?’ Embla said. ‘When they came for Nammu’s heart before, there were many fighters. The elk herders battled them and won. So the legend goes.’

‘It’s just us,’ said Liska. ‘Nobody would believe us. They thought Nammu was just a story.’

‘And here it is only me,’ said Embla. ‘All the elk herders have died or moved away. The walking ice is eating Nammu. Already half her roots are dead. Soon the rest will be, too.’