The metropolis of Lanzhou, native city of director Yuan Zheng, lies along the Yellow River. Over a four-year period, he attempted to film the signs left by the works undertaken on the river in the 1950s by Chairman Mao. Presented as a national feat in the official History books, these transformations are still perceived as a catastrophe by some. A Yellow River that is no longer yellow, rivers reduced to streaks of dirty and pestilent water, with considerable environmental damage and irreversible climate change. But, in a quest which takes a unexpected post-apocalyptic fictional turn, Yuan Zheng comes up against a form of general amnesia with which the inhabitants are struck: in Lanzhou, people continue with their life and its mundanities, and build colossal buildings using “trans-contemporary” architecture. The director, even while employing free and heady editing, moving from black-and-white to colour, cannot recover the traces of the catastrophe. It is as if it had all been forgotten. And what if this were to be repeated in the not-so distant future, post-pandemic?