Double Track Puzzle.

Zhan Peng, son of a martyred railroad cop, fulfills his dream to serve in his father's former post at Xiatong railway, only to find the job more complex than imagined. Initially distrusting veteran officer Tu Hongjiang, his suspicions peak when Tu behaves strangely during a drug trafficking case. However, Tu gradually proves his integrity through actions, and the two build mutual respect while solving cases together, ultimately uncovering and arresting the hidden mastermind.