story. It is set in the future after Earth dies and the human population has settled on Mars. They have worked together to create a habitable atmosphere on Mars, but saboteurs destroyed much of the work and set progress back greatly. The humans live in several biospheres spread out among the Martian landscape. Each biosphere has a certain function for the community as a whole. One engineers seeds, while another houses scientists that work on replicating, another creates hybrid animals from DNA and others work on various other projects. At each biosphere, there lives a group of messengers called Runners. The humans have lived in these conditions for several generations. Their goal, always working toward a sustainable living environment, is impeded by dissension and sickness. Wren is a girl and must adhere to societal rules that say she can only contribute by either marrying a Runner and maintaining one of their outposts or by producing offspring for the baby exchange, a way to prevent problems from inbreeding. Wren is left alone with her mother as the men in the family are off on Runner's business. When her mother is taken ill, she is left with the decision to stay and tend her mother, possibly watching her die, or to reject societies mold they have set for her and try to find help.
I loved the attention to detail that was afforded to the dynamics of flight for the Runners. I was scared of the creatures and still have several ideas in my head about what they are. I was so invested in Wren's story, the decisions she would make and their outcomes, that I would have read this story in one sitting, but I had to go to work. This is a great book for young and old alike. There are realistic consequences to each choice made and there is a love story that is fitting but doesn't take center stage. I only wish there was a sequel.