Fifteen years after the events of Currents, a new generation of Ables--including Phillip and Emmaline's kids, Emily and Henry--are learning to navigate their powers and beginning to understand what it takes to be a hero.

A new killer is threatening the custodian world: a strange blood disease that only targets those with custodian DNA. The disease is wiping out the older population of heroes, and doctors are far from understanding it, let alone curing it. Overcome with fear that the disease will cause custodians to become extinct, the humans begin ramping up military spending, straining relations between humans and custodians. Phillip comes under fire as one of the most visible and important custodial board members, and hope looks slim when Phillip's father is diagnosed with the disease.

Phillip, Emmaline, and the other Ables are caught between the crumbling society of custodians while protecting and raising their fledgling-hero kids. But Emily, Henry, and their friends have plans of their own to help their parents, and begin following clues left in a notebook written by Bentley Crittendon with the belief it will lead them to his secret lab where the cure is. The problem? A group of masked custodians are after it too, and they're willing to do anything to get to it first. In the epic conclusion to The Ables series, three generations of Ables must unite in the race to uncover the secret lab--and the madman who created the disease, who is bent on destroying them all.