Rumi Sabzwari has spent his entire life behind the armored walls of St. Iago, which protect citizens of the Union of Upper Cities from the outside world's environmental devastation. When rebels infect his father with a fatal virus Rumi leaves, desperate to find a cure. In the ruined city of Paraíso he meets Paz, who agrees to guide him on his journey. As they travel together, Rumi finds himself drawn to Paz. But she knows more about Rumi's father's illness than she's saying and has her own agenda. Can the two learn to trust in each other -- enough to imagine a different world?