Ardal took a turn for the worse, and the Inis Eala healers became very busy indeed, brewing drafts, applying poultices, trying to draw the poisons out with leeches. Walking into the infirmary, I heard the desperate rasp of his breathing and smelled the miasma of sickness and defeat. My own role included everything from sweeping the floor and washing bandages to holding Ardal’s hand by candlelight and willing him to take one more breath. I fell into bed so exhausted that I hardly knew whether I was awake or asleep. I dreamed of great waves, perilous rocks, men screaming in despair. In the mornings I woke with thumping heart and clammy skin, and murmured a prayer of thanks that the nightmare was not real. My first act on rising from my bed was to go through and check that Ardal was still breathing.

He no longer looked at me with recognition. When he could summon sufficient strength to open his eyes, he seemed to be gazing on fathomless dark. He did not speak, either in Norse or Irish. Muirrin looked shattered, Evan somber. Even Gull had stopped saying our patient might survive, though he remained calm and composed, attending to anything and everything with gentle hands and kindly words.

I did not go to the seer’s cave. I did not go anywhere much; the four walls of the infirmary were the boundaries of my world. I had saved Ardal’s life. The runes had shown a mission for him, a call to action I was coming to believe must be obeyed by the two of us. He couldn’t die.

It was hard to pray, hard to conduct a conversation, hard even to think straight. My stomach was knotted tight; my head was muzzy with unshed tears. Everything was awry. I had tended to the sick before, but that had been nothing like this. I felt, oddly, as if part of me were in that man lying on the pallet, fighting Morrigan’s will. If he died, part of me would die with him.

Eventually a day came when Muirrin ordered me out. “Go on, Sibeal. You must have a rest from this, even if it’s only for a morning. Go and see Clodagh. Or chat to Biddy, and let her feed you.”

“I can’t. What if he dies while I’m not here?”

Muirrin put her arm around me. “You can’t keep him alive by sheer force of will,” she said. “We’re doing the very best we can, Sibeal. You know that. But you won’t help Ardal, or us, if you get so exhausted you become sick as well. Go on, now. Get some fresh air, at least.”

Biddy was in the kitchen, gutting fish. She sat me down and put a bowl of porridge in front of me.