Earth has long since been ruined by millennia of environmental carelessness. Most of the human race has moved out into terra-formed moons and asteroids. They seem happy enough. But many long for wide open spaces, the feel of rain on their faces, wind in their hair, blue sky like a bowl over their heads lit by a warm sun. Such people demand a new world to call home. But Earth-like planets are exceedingly rare, and those without intelligence rarer still. In fact, none of the three Earth doubles found so far have been uninhabited. Crandall Knight doubts Novum Terra will be, either. The Hero Tree tells a tale of two worlds and two peoples as they struggle to come to terms with each other.