The protagonist, Shervane, lives on a planet with one sun called Trilorne. The planet is nearly always light because the sun remains high above the land. Only in the winter does the sun dip down below the horizon in an area called “the Shadow Land” (104). Shervane is curious about his world, wondering what lies in every direction. He has heard legends of ships sailing north only to have to turn around because of the extreme heat of the sun. He wonders if there is such a thing as the “mythical Fire Lands” (105). Because of the position of the sun, “all the inhabited countries of Shervane’s world lay in the narrow belt between burning heat and insufferable cold” (105). Shervane learns about the workings of his world, including the way time passes and how crops are grown and harvested, from his father, Sherval. Shervane’s tutor, an older man named Grayle, teaches him about the philosophical aspects of life.

When Shervane comes of age, Sherval takes Shervane to the top of a small hill and shows him a dark line on the horizon. This, his father explains, is “the Wall” (107). The following spring, Shervane leaves his family and sets out on his journey to discover his world.