Chapter 20 - Chapter 24. Summary

In Chapter 20, Arthur and Fred are still being led to the GHQ by Troop Lieutenant Jarrow. They outrun the New Nithlings and stop their Not-Horses for the night, sleeping on the ground. Jorrow tells the boys they will be at the Citadel in the afternoon. Along the way he teaches them how to tell the boundaries of the tiles. Mostly the border tiles can be determined by their yellowing plants and trees. The tiles shift at certain times and their new positions can be determined using a Ephemeris. He also tells the boys that things at the Citadel have been confusing since Tuesday was replaced by Lord Arthur. At the mention of his name, Arthur remembers everything. He also remembers Saturday's note which threatened his family. They resume their travel in the morning where they come upon a water...