Chen Mo, the God of War on the border, single-handedly wiped out the enemy nation's Apocalypse Special Forces Brigade five years ago, earning the codename Mountain Guardian. After completing his mission, he retired and returned to Jiangcheng under an assumed name. All he wanted was to look after his frail, frequently ill wife and five-year-old daughter, living an unremarkable life as a security team leader. On his first day at work, the old man he casually helped up turned out to be Jiangcheng's richest man. The troublemaking punks he stepped in to stop were backed by the underground kingpin. Everyone thought the security guard was finished, until one untouchable big shot after another knelt before him. But Chen Mo discovers that Apocalypse was never truly destroyed, and that his wife's mysterious illness and his daughter's different-colored eyes are both connected to that bloody battle. The moment foreign mercenaries set foot in Jiangcheng, Chen Mo knows he can hide no longer. This time, though, he has more than just the nation's borders to protect.