The occupants of a steam train will be surprised by the attack of a huge number of crazy and ravenous rats.

A Chinese Department of Health junior clerk Su Zhenghuai is with his eldest daughter Su Wei and son Su Yuexuan are on their way to visit relatives in the provincial city when they meet the long-lost second daughter Su Ling. Unfortunately, the train is attacked by rats. Su Yuexuan is bitten by a rat and goes into a coma. In order to save his young son and many bitten passengers, Su Zhenghuai and Su Wei decide to make the dangerous venture to Xiaobaihe Hospital to get medicine.