When a mysterious and charismatic woman insinuates herself into a fringe religious group, its dozen members wonder whether she is a lunatic, a con artist, or a messiah. Sophia quickly upends the routines and expectations of the group–the last Christians in the inhabited solar system–while Peter, their struggling leader, becomes increasingly obsessed with her. Before long, Peter finds himself following Sophia on a perilous interplanetary adventure which may cost both of them their lives.