Then what was on the other half of the map?

In his view both were part of the same map.

He alone had access to the other half of the map.

There was a star in the center of the map.

There was a little star at the very center of the map.

He was sure he'd been looking at the right side of the map, near the edge.

He knew where they were from one of his many maps.

At least everybody is working with the same set of maps.

"I'll trade for news of my father and a map to find him with."

All of the maps are written by public school teachers.