70 years after the events of THE DEATH CURE, when Thomas and other immunes were sent to an island to survive the Flare-triggered apocalypse, their descendants have thrived. But when a rusty old boat shows up one day with a woman bearing dark news of the mainland, a group of the islanders decide to embark back to civilization. There they find that many have evolved into a more violent, intelligent version of Cranks due to a new string of the virus, and they are hunting those whose ancestors were sent away by Ava Paige. The islanders will have to survive long enough to figure out why they are hunted and what it means for the future of humanity.