It was terrifyingly cold here; coldness like a living thing that pressed against your flesh, searching for a way to crawl in through your pores and smother the failing core of warmth inside your body. Hester felt as if it had already crept into her bones; she could feel it gnawing at the furrow Valentine’s sword had left in her skull. But she was still warmer than poor Tom, who had been out on the starboard engine pod for the past hour, trying to chip away the ice that had formed there and make repairs.

She led him aft and sat him on the bunk in their cabin, heaping blankets and spare coats over him and snuggling in beside him to let him share her own small store of warmth.

“How’s Professor Pennyroyal?” he asked.

Hester grunted. It was hard to tell. The explorer had not regained consciousness, and she was beginning to suspect he never would. At the moment he was lying on a bed she had made up for him in the galley, covered with his own bedding-roll and a few blankets which Hester felt she and Tom could ill spare. “Every time I think he’s finally gone and it’s time to chuck him overboard he kind of stirs and mutters and I find I can’t.”

She dozed off. It was easy and pleasant to sleep. In her dreams a strange light filled the cabin; a fluttering glow that flared and shifted like the light of MEDUSA. Remembering that night, she cuddled closer to Tom, and found his mouth with hers. When she opened her eye the light from her dreams was still there, rippling across his beautiful face.

“Aurora Borealis,” he whispered.

Hester sprang up. “Who? Where?”

“The Northern Lights,” he explained, laughing, pointing to the window. Out in the night a shimmering veil of colour swung above the ice, now green, now red, now gold, now all at once, sometimes fading almost to nothing, sometimes blazing and billowing in dazzling streamers.

“I’ve always wanted to see them,” said Tom. “Ever since I read about them in that Chung-Mai Spofforth book, A Season with the Snowmads. And here they are. As if they’ve been laid on just for us.”