How does the author use foreshadowing in Pretties?

In Part III, Tally finds a way to escape the reservation, but it means leaving behind her new friend, Andrew. Tally is outraged by what is being done to Andrew and his village, but there is little she can do about it at this point in time. However, Tally hopes to be able to do something someday, foreshadowing possible events in the third book of the series.