Set in the Second Phase Offensive of the Korean War, "The Battle at Lake Changjin" tells an epic historical tale: 71 years ago, the People's Volunteer Army (PVA) entered North Korea for battle. Under extreme freezing conditions, the troops on the Eastern Front pursued with fearless spirit and iron will, as they courageously fought the enemy at Lake Changjin (also known as Chosin Reservoir). The battle was a turning point in the Korean War and demonstrated the courage and resolve of the PVA.
After causing the accidental death of one of the suspects during the interrogation of a violent and brutal home invasion homicide case, all five police officers of the 3rd Criminal Investigation Brigade were sentenced to prison and the brigade disbanded. Upon release, former team leader Cheng Bing, reunited with his old teammates and enter a decade long persistent and relentless pursuit as mere ordinary civilians to hunt down the remaining suspect of the unsolved murder.