“This won’t.” Shef rolled the vellum up, thrust it aside. “But the idea of it may. We need to know more important things. Remember—if we had not known where Riccall was, that day in the snow, we might have been cut off and destroyed in the end by the churls. When I set off for Beverley, I knew the direction, but I would never have found the minster if we had not had a guide who knew the roads. The only way I found Bridlington and the man who could sail us out of a trap was because I had traveled the road already.

“You see what I mean? We have plenty of knowledge, but it all depends on people. But no one person knows enough for all the things we need. What a mappa should be is a store of knowledge from many people. Now if we had that we could find our way to places we had not been before. We could tell directions, work out distances.”

“So we make a knowledge mappa,” said Brand firmly. “Now tell me about rich.”

“We have one other precious possession,” said Shef. “And this we did not get from the Christians. Thorvin will tell you. I bought it myself. From Munin, the raven of Othin. I bought it with pain. Show them, Thorvin.”

From inside his tunic Thorvin pulled a thin square board. On it were lines of small runic letters, each one scratched with a knife and then marked out with red dye.

“It is a riddle. The one who solves the riddle will find the hoard of Raedwald, king of the East Angles. That is what Ivar was searching for last autumn. But the secret died with King Edmund.”

“A royal hoard,” said Brand. “Now that could be worth something, all right. But first we have to solve the riddle.”

“That is what a mappa can do,” said Shef firmly. “If we write down every piece of knowledge we can find, in the end we will have the right number of pieces to solve the riddle. But if we do not write them down, by the time we come on the last piece we need we will have forgotten the first.

“And there is another thing.” Shef struggled with an image in his mind, a trace of memory from somewhere, of looking down—down on the land in a way no man could ever in reality see it. “Even this mappa. It has one idea. It is as if we were looking down on the world from above. Seeing it all spread out below us. Like an eagle would see it. Now that is the way to find things.”

Guthmund the skipper broke the considering silence. “But before we see or find anything, we have to decide where we go now.”