“The heathen is exalted,” Ieremias said, “and must be brought low.”

“You know Sköll lives in a high place?” I asked carefully, never quite sure whether Ieremias was listening to me, let alone telling me the truth.

“Very high, lord! His place of refuge touches the sky and lies above the pit of silver.”

I stared at him. “You know where it is?”

“Of course I know!” He suddenly sounded entirely sane. “Do you remember Jarl Halfdan the Mad?”

I shook my head. “Should I?”

“He lost his wits, poor man, and led an assault on Dunholm. Jarl Ragnar killed him, of course, and then we all went north and laid his home waste. That was before God called me to His service.” Ieremias used one end of his intricately embroidered pallium to blow his nose, making Father Swithred flinch. “Halfdan the Mad’s fort is a very nasty place, lord! The Romans built it.”

“Where is it?”

“Lord, Lord, Lord,” Ieremias said, evidently calling on his god to help him remember. “You know the road from Jorvik to Cair Ligualid?”

“I know it.”

“About an angel’s flight from Cair Ligualid another Roman road goes north into the fells. It climbs, lord. If you follow that road you’ll find Halfdan’s fort. It’s lost in the hills, very far and very high.”

“Heahburh,” I said.

“It is high!” Ieremias said. “And the higher you climb the nearer you come to God. I was thinking of building a tower, lord.”

“How far is an angel’s flight?” I asked.

“A very high tower, lord, to make it more convenient for God to speak with me.”

“Angel’s flight,” I reminded him.

“Oh! Just a half-day’s walk, lord.” His face lit up as he remembered something. “Halfdan’s fortress lies above the headwaters of the South Tine. Follow that river’s valley and you must come to where you can smite him, but pray, lord, pray! Halfdan’s fort is formidable! A wall, banks, and ditches, but I shall beseech God that he grants you good smiting. The Lord of Hosts is with you, you cannot fail to smite mightily!”

“But how can you be certain that Heahburh is Halfdan’s fort?” I asked, praying that the answer would not be that his god had told him.

“I can’t be certain,” Ieremias said, sounding perfectly sane, “but all the reports say that Sköll lives above the pit of silver. Where else can it be?”

Some instinct told me that Ieremias’s recollection of Ragnar the Younger’s raid was the truth, which meant that Heahburh lay not too far south of the great wall, and not too distant from the place where my son had been ambushed. “The pit of silver?” I asked him.

Ieremias looked at me as though I were the mad one, then understanding dawned. “There were lead mines there, lord.”

“And silver is smelted from lead,” I said.

“From the darkness cometh light,” Ieremias said happily, “and silver must be given to the poor, lord.” He looked pointedly at the sling-stone I was still holding. “That is a very valuable relic, lord. King David himself handled it!”