Considering the underground as both a metaphor and a manifest reality, Zheng’s film Sinking Latitude focuses on a myth about underground flooding. The city where the story takes place (Zigong city in the Sichuan province, China) has a history of salt mining that spans more than 2000 years, and generations of residents who have lived there have passed down a prophetic myth for centuries–that due to excessive mining, the city's underground has long been hollowed out and depleted, filling with salty brine, and that one day, when an earthquake occurs, an underground flood of salty liquid, the mine itself, will surge out and engulf the city.