In 1978, on a train bound for Sankeshu from Dalian, young police officer Wang Xin was injured during an arrest during his first duty. However, as a blessing in disguise, he met Ma Kui, an old criminal police officer from the railway police. The two became masters and apprentices, fighting side by side. The front line of railway police. On this railway line, over the past 40 years, they have experienced the era of steam locomotives, electric locomotives, and high-speed trains, and witnessed the great achievements of the motherland and the tremendous changes in people's lives. The front-line railway police officers represented by Wang Xin and Ma Kui have been engaged in anti-piracy, anti-trafficking, anti-narcotics, line patrol, guarding, cracking down on theft, robbery, gangs and evil. For decades, they have solved major cases, solved small cases, and provided passengers with Sending warmth and harmony. In order to protect the safety of people's lives and property, railway police officers even sacrificed their precious lives. Passengers coming and going on the train bear different marks from different periods, showing the warmth and warmth of human nature and the various aspects of life. The old and new generations of police officers have also been sublimated in their life experiences, and their loyal police spirit has been passed down from generation to generation.