Part 4/9:

Meanwhile, Zhang's son, intrigued by a strange sound, inadvertently brings a series of misfortunes upon the passengers by removing a cloth that conceals a cat. A misguided action leads to a man banging on the roof, causing thousands of rats to flood into the train's compartments, attacking anyone in sight. The turmoil intensifies and, despite the major's coordination, the officers lock the compartments, leaving passengers to fend for themselves.

Unexpectedly, Zhang realizes that the rats are repelled by sunlight, enabling him to free himself from his shackles. His journey of warning other passengers, however, is met with skepticism and ridicule. As the distress around them heightens, with more of the unrelenting rats spilling into the compartments, Zhang seeks an escape path.