Set in a world where the climate has already changed, this is the final book in beloved author Jackie French's Children of the Valley series. With Desert Wind as their guide, Possum and Mopoke have once again left the Valley to brave the world outside, where it's harsh, dry and so hot you can't go out during the day. It was supposed to be a short journey, following the creek up to the salt pans, but just like all their others, that's not how it turns out. This time, they hear a strange, eerie noise, like nothing they've heard before. Is it a machine? An animal? Or something else? Is it dangerous?