Immediately after the explosion that killed Noah, a new bomb shakes the group to its core. With casualties, injuries and no shelter, survival hangs by a thread. While some try to keep the camp going, others venture deep into the island... where something has been waiting decades to be discovered.

With supplies exhausted and Máximo on the brink of death, the group risks everything trying to open the armoured door of the Soviet base. But what they find on the other side is not just supplies: there is life on that island no one expected, and not all of it is welcome.

The group finds a way to escape the island by converting their boat into a sailboat. But while racing against the clock, one of the expedition members conceals an unsettling transformation that threatens to change who she is, and the two young Russians reveal secrets about their origins that no one expected.