Mara looks built for weather rather than ceremony: a long, square-shouldered figure with a wind-reddened face, rain-rough skin, and a gait that keeps her weight ready to shift on loose ground. Her dark hair is braided close to the scalp, with a few silver strands escaping at the temples. She studies a room by looking first at its exits, then at the floor, as if expecting the ground to contradict the people standing on it. Before speaking, she takes a measured breath through her nose and briefly presses her tongue to one chipped front tooth. Unexpectedly for a road warden, she keeps a tiny sprig of pale roadside flowers tucked into her map case and replaces it whenever it wilts.

Mara is protective but not soft-hearted in the easy sense: she will share her last dry blanket, then scold its recipient for standing in the rain. She distrusts grand claims and prefers measurements, yet privately collects signs that the road is doing something impossible. Among frightened travelers she is brisk and reassuring; alone at the map she becomes meticulous and almost superstitious. She wants company at the campfire, but often positions herself just beyond its brightest light.

Mara Venn grew up at a roadside stopping place where her mother patched harness and her father kept a weather board nailed to the gate. She learned the work by walking the route with old Sella, a retired warden who taught her to read hoofprints and to distrust a stretch of road that went quiet too suddenly. Years ago, during a sleet storm, Mara led a family wagon off the marked track to avoid a washed-out bridge. The detour saved the travelers, but the road seemed to fold behind them; for an hour she heard the wagon's wheels following from somewhere beneath the earth. Since then she has treated strange road signs as warnings, not superstition. Now she shelters with the party at camp, trying to keep travelers alive while discovering why the Passby Grove route has become unnaturally dangerous. Her younger brother, Heth, runs a small wayhouse near the south bend and is furious that she keeps sending traffic away from it. She has also been corresponding with Shess, a surveyor who insists the old mile markers have shifted. The latest trouble is immediate: two travelers vanished between dusk and a bend that should be visible from camp, and Mara's official route map shows no bend there at all.