A stranger arrives in Thibodaux, Louisiana, in the autumn of 1997, carrying only a leather satchel and a brass compass. He claims he's measuring the shadows along the bayou to chart a map no one has drawn before. Luna's grandmother lets him stay in the back shed, and for three weeks he walks the banks at dusk, taking notes on the length of shadows cast by cypress trees and hanging moss. But the shadows don't match the sun's position. They grow longer as the sun sets, always pointing toward a stretch of water that has no bottom. Luna, then twelve years old, follows him one evening and learns what he's actually charting — not the shadows of the present, but the shadows of things that have not yet happened. The story ends with her alone at the edge of the water, waiting for something she knows is coming.