The arrival of the last known transporter from Earth gives some new hope for the residents of Carpathia. Loyalties end up being tested though as the head of Forthaven's expeditionaries attempts to break away from the settlement.

Cass, Fleur and Jack leave the settlement to try and find a a missing survival shuttle. Stella and Tate are confronted by their former foe Julius Berger.

It is predicted that a super whiteout of unprecedented strength could hit Forthaven. Stella uses Tipper's mathematical ability to predict exactly when the it could happen and Tate begins to lock down Forthaven. Fleur, unaware of what could happen takes the AC baby back to Rudi. Cass ends up running into an old flame called Trix who is about to be married the following day.

A rogue AC enters Forthaven and ends up attacking one of the citizens which prompts the PAS officers to take action in an effort to control the situation.

A man arrives at a bar in Forthaven with a load of diamonds and stories of "bodies" outside the compound. He claims that he lives by Carpathia's ocean which seems to be impossible as it's known as a radiation hotspot. After a fight breaks out and Cass and Fleur are called in and they end up following the man.

Three of the expeditionaries missing outside the settlement for several days and as hope of locating them dwindles one of them, Josie Hunter, arrives back at the settlement. Josie is pleased to be back with her family and Forthaven celebrates her sudden return. Her children though can not communicate with her and reports of her attack on a fellow XP outside the perimeter begins to circulate.

Tate believes that there is a superior host force on Carpathia and Stella bcomes determined to work out a way to talk to it. Cass discovers a note that threatens to expose his real identity. After getting drunk he picks up a woman and takes her home. The following morning he discovers her going through his belongings, opening the box that holds his witness protection documents. She manages to get away after he thinks she is the person who sent him the note.

After a deadly virus breaks out on Forthaven, Tate and Stella are concerned that it's the host force answering their attempts at communication. Berger thinks that the ACs are to blame for the outbreak after revealing a devastating secret about Fleur and attempts to bringing down Tate's government and introduce a whole new order.