When King Herod sends his soldiers to kill all the children in Bethlehem, Joshua escapes and joins his uncle, Joseph, who is going on a trading trip to Britannia. But Herod's cruel solder, Flavious Gracchus, has found out about the boy, and is now hot on his trail.

Somewhere in the misty north, on the outer fringes of the Roman empire, Gen lives with his family in a village on an island in a lake. News has just reached them that their distant relative, Joseph, from Arimathea, is coming to visit. He is a famous hero who trades in metals. Gen is so excited when his mother agrees that he is now old enough to go with his father when they travel south to meet him.