Anti-Japanese War Company Commander Shen Shanhe encounters a spacetime anomaly on a fire-ravaged frontline and accidentally time-travels to the modern metropolis. Having weathered the trials of time, the rivers and mountains remain, yet human society conceals hidden evils in the dark. Endowed with a soldier's integrity, Shen Shanhe befriends the justice-driven Lin Wanqing. Together, utilizing meticulous investigative wisdom, they silently gather evidence of criminal gangs' wrongdoings. Adhering strictly to the bottom line of modern rule of law without crossing boundaries, he hands over the fully compiled clues to relevant public service departments, assisting in uncovering layer after layer of dark covers and fighting against the evil forces and behind-the-scenes protectors hiding in the city. Defending the national territory in a past life, protecting the common people in this life. A guardianship spanning across eras continues to unfold in the bustling metropolis.