Sixty years after Earth's destruction, humanity survives aboard five generational ships. Maren has spent her life on the ship Reverence, raised and trained by her mentor Lucas Troy. Until one day, she overhears Lucas speaking with one of the ship's ruling elected ten.

She learns the truth: she is being groomed to become the next Reaper, the ship's enforcer responsible for population control and upholding the oppressive Thirteen Laws. When the Elected Ten order Maren's execution, Lucas helps her escape to the ship's lowest deck, where she uncovers the real reason Reverence remains in orbit.

They are searching for Liberty, a sister ship hidden on Earth after stealing something critical, a treasure Maren believes could earn her a pardon. With help from her friend Jason, Maren stows away on a shuttle to a mining compound on Earth. There, her crew-mates discover her presence. Her revelations split the group: some believe her, others want to turn her in for a reward. A fight breaks out, pinning brother against brother.

Reverence retaliates by bombarding the compound, scattering the survivors across Earth's toxic surface. Injured and trapped in a pit, Maren is urged to climb out by a mysterious man with eyes as black as space. She survives, earning the nickname Inferno among her crew.

Maren awakens aboard Liberty, where she meets Kai, but even he holds dark secrets of his own. She discovers that Liberty thrives. Its people are fed, its gardens flourish, and its bees pollinate freely.

Maren returns to Reverence, believing the captain can be reasoned with and the true enemy is the generational lies that have shaped their society.