When Hollis Timewire and her friends are miraculously rescued from execution at the hands of President Camille, they discover there are other Diseased Ones in hiding—and their vast, clandestine society is more extensive than Hollis ever could have imagined. They are led by Arthur Evandrum, a fellow Diseased One who has big plans for Hollis.

As she acclimates to a new way of life, Hollis is charged with seizing the Area 19 Testing Center and assassinating President Camille. But she pushes back. She fears killing the president will send a message that the Diseased Ones are just as dangerous as history says they are. Working with Jonah and her friends, both old and new, Hollis is under the wire to take over the government with as little bloodshed as possible.

Questions and doubts arise as she formulates a plan, and a disturbing revelation thwarts her strategy, leading to a series of unspeakable tragedies that change her world forever.