Chen Shoushan, a 57-year-old chief equipment engineer earning a monthly salary of 30,000 yuan, is reassigned to guard the underground parking garage by newly appointed property manager Song Zhiwei because she believes he does nothing but watch surveillance cameras and wander around. When a malfunctioning water pump leads him to discover an underground drainage pipe that was never properly dealt with eight years ago, disaster strikes. Torrential rain floods the underground garage, and the power supply to several residential buildings is in danger. The veteran chief engineer, once dismissed as useless, becomes the key to the emergency rescue. However, an old engineering document bearing his signature puts him at the center of the blame. Facing workplace prejudice, vested interests, and unresolved problems from the past, can he prove his true worth? What exactly does a monthly salary of 30,000 yuan pay for?