It tells the story of Ma Kui, an old detective who has returned from his hometown for ten years, and Wang Xin, a young and outstanding police officer. The two masters and apprentices went from being dissatisfied with each other, full of conflicts and misunderstandings to working together and working together in a tacit understanding.Through the various aspects of life on a train and the warmth and warmth of human relationships among a group of neighbors, we witness the innovation and development of the great motherland, and the story of the inheritance of the spirit of the new and old generations of railway police officers.