Paleontologist Helena Walker awakens on an island full of strange beasts.

Helena is on the run from Nerva's scouts, when she meets a new ally called Meiyin.

Helena and Meiyin find new allies in a treetop village led by a Lakota warrior and his adopted daughter; a sickness ravaging the villagers brings everyone together in a quest to search Pteranodon mountain for a cure.

Helena and her allies attempt to liberate the prisoners at a brutal mining camp; when Helena's plans go awry, she and Alasie are captured.

Nerva unleashes a punishing surprise-attack against John's village.

Helena, John, and Henry risk everything to rescue Meiyin from Nerva.