After the Gray Mist descends, a “danger countdown” appears on everyone's wrist. Lin Che, a food delivery rider, can hear broadcasts from the future. He thinks he's escaping a disaster, but step by step, he discovers the truth: the Gray Mist isn't a natural disaster, and the safe zones aren't shelters. They're part of a citywide lockdown experiment spanning seventeen years, and he himself is the experiment's only variable who “shouldn't still be alive.”
