Leif's ship strikes a rock while traveling along an enemy's coastline in the fog. While the Vikings try to repair the hole in their ship's hull, Brother John leaves the company, weary of Finn's disbelief about the usefulness of "the black rock" - a magnet - for navigating in bad weather. Leif chases him and the two men stumble upon an outcropping of the desired rock - along with a rich vein of ore carefully guarded by their enemies.
—David Bassler