Li Qiuming is a young trainee at a digital mapping company. His job is to survey the streets of the ever changing city and keep the mapping system up to date. To make ends meet, he installs video cameras at public venues, but hides his side job from his strict father who is a senior editor of a government-run magazine. One day while out surveying, he has a brief encounter with a beautiful young woman who disappears into a secluded alley. He learns that the data he collected of the street will not register in the mapping system. The street has disappeared as if it never existed. Desperate to reconnect with the mysterious woman he continues his investigation of the unmappable street only to discover something that will change his life forever.