In the 37th year after the Great Collapse, the world fell apart. In the wasteland, the courier is the only messenger.
Lin Mu is the most senior courier at Laoyi Station and has never lost an order in seven years. He lost his memory in a fire seven years ago. The only thing he owned was a pocket watch that stopped at 3:17.
One day, he received an unprecedented order - to send a girl to Beacon City.
The girl is Aying, fourteen years old, suffering from "dust disease" and her memory is disappearing. All forces are looking for her because she hides the secret about the "Firefly" project in her mind - and that secret is actually related to Lin Mu's past.
When the true face of Lighthouse City was revealed, and when Lin Mu discovered that he had been Aying's guardian, he faced the most difficult choice in his express delivery career: complete the order, or protect the promise?
He tore open the order.
"From now on, you are not a courier. You are my promise."
This is a story about amnesia and search, commitment and betrayal.
In a world where everything is crumbling, some things must be delivered.
