Archer has been banished from the colony, falsely condemned for the rape of Celine. But Zack doesn't believe in his brother's guilt, so an expedition is launched into the danger zone. Unbeknownst to the rest of the community, the teens go to look for Archer...if he is still alive. The expedition will not be without risks though, nor without unpleasant surprises... Back at Fort Apache, confusion reigns and tensions are at an all-time high, as the adults look to safeguard the young and keep the colony intact. But with a "white wave" approaching, is it already too late?
Upon returning to Fort Apache, Zack decides to confront Celine, pushing her to tell the truth in order to clear his brother’s name. But the mounting pressure may be too much for her to handle… And another expedition into the danger zone is launched, this time by the adults, to locate and recover the missing supplies from the train—supplies that the colony desperately needs to survive.