Devon Three is one of three small, barely habitable planets orbiting the system’s star. Located at the outer edge of its primary's habitable zone, the planet is an icy, rocky world that leads an erratic, elliptical orbit lasting 5,470 local days, each of which lasts only twelve standard hours. Being so far from the sun, only weak sunlight reaches the planet itself.

Although the planet’s atmosphere contains an abundance of greenhouse gases—so much so that the air is toxic to most humanoids—little infrared radiation reaches the planet’s surface, leading to mean temperatures at least fifty degrees below zero during the day, planet-wide. Despite the hostile environment, or perhaps because there are no local air pollution laws, the planet’s surface is entirely covered in mines, ore refineries, smelters, and factories that turn the planet’s abundant raw materials into ingots, bars, and powders to be exported throughout the Devon system. As there is little to no agricultural activity on the planet, ninety-four percent of the sustenance needed by the world's population is imported from Devon Four, the only planet in the system where crops can be cultivated and livestock raised for meat and milk.