In a far-future Scotland where alchemy has turned most people into hungry ghosts and given the survivors amnesia, Courier is the oldest of seven clones. Living in a secluded laboratory, she faithfully carries out the orders of her creator, the Professor. Then she's sent out into the world to gather intelligence on a settlement- with her sisters' lives depending on her obedience.

It should be a simple mission. Then she meets Sear.

Sear is a messenger, making the perilous journey between settlements on foot. Haunted by cryptic memories of a lost spouse and children, she's brave and selfless, even if she cheats at board games. Sear makes Courier long for possibilities she didn't even know existed. But if she chooses to save Sear and her people from the Professor's plan to eradicate humanity using mutant ghosts, her sisters will die.

Courier can't run from her problems. She can only keep running.