As a global calamity descends upon the world, Gu Heng awakens a divine kingdom within an unnamed graveyard, only to discover that every use of its power comes at a price, with all debts settled at midnight. To uncover the truth behind the dark calamity of twelve years ago, he and Shen Zhixia board the mysterious Midnight Express, traveling through the old city, graveyards, and a carriage filled with lost items. Amid rule-bound debts and a countdown to death, they search for a way to survive while gradually unraveling the secrets behind the cycle of fate.