On the southern border where heavy rain poured down, cries beside the boundary monument pierced the darkness. Lu Chen, a police officer on patrol, discovers Xiao Man, a baby girl abandoned by human traffickers. Due to the adoption conditions, he could not give Xiaoman a formal identity, so he could only raise her at the border police station in the name of "brother."
In order for Xiao Man to go to school and live like other children, Lu Chen tried his best to apply for a household registration, but encountered obstacles everywhere and was even called a "dog-licking policeman." During the year of Xiaoman's college entrance examination, he was rejected because of his status as a "black householder". During the investigation, Lu Chen accidentally uncovered an "undercover murder case" from ten years ago - it turned out that Xiaoman was actually the orphan of a martyr!
However, as soon as the truth emerged, the smuggling group behind it was alarmed. They regarded Xiaoman as a "living pawn" who hid evidence back then, and tried every means to silence him. Smugglers kidnapped Xiao Man to force Lu Chen to hand over key information.
But these gangsters don't know that in the years of being with Lu Chen, Xiaoman has already learned everything her brother taught her. The wind at the border, the patrol dogs, and even the marks on the boundary monument are all their "hidden comrades."
When Lu Chen broke into the smuggling den single-handedly, Xiao Man saw the right opportunity and used a coded code to convey information to the outside world. At the tense moment of the confrontation, Xiao Man's eyes were firm and he shouted at the gun: "Although he and I are not related by blood, he has protected me for fifteen years with his life! If you want to touch him, you must step over my body first! "
In this border full of dangers and challenges, they protect each other in the darkness and the lights of thousands of families behind them with a bond that transcends blood ties.
