Palaeontologist Helena Walker awakes on an island filled with dinosaurs.

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.

Meiyin attempts to turn the newly liberated villagers into soldiers, but her comrade, Henry, argues against her military leadership; Nerva stages a counter-attack against John's village.

Imprisoned in Nerva's fortress, Meiyin recalls the tragic mistakes of her past; Helena, John and Henry attempt to stage a daring rescue.