Mechanic Tian Xiangdong sets the price of a front brake pad replacement at 480 yuan. However, his insistence on using genuine manufacturer parts and performing a complete inspection earns him a reputation as a dishonest businessman among drivers. A rival quick-repair shop across the street steals his customers with a low price of just 150 yuan, but drivers who have their brake pads replaced there soon experience dangerously soft brakes. As strange noises begin coming from the fleet's vehicles and engines start making muffled rumbling sounds, Tian Xiangdong discovers a hidden truth behind the substandard parts and counterfeit oil. Anonymous threats soon follow.