A rooftop assassination attempt introduces violinist Dahlia Choi to a world of masked killers and buried history. When she survives, the event sets off a chain that unravels century-old secrets: a sacred Jade stone of immortality, the Moon Tribe who guarded it, and a massacre that tied two families together through fate and blood.
Seo Jaemin — a fierce, green-eyed fighter — and Dahlia form an uneasy alliance that becomes love as they chase clues from Hwayang Valley to Mount Seonghyeol. Detective Choi Dojoon and NIS agent Lee Chaerim (Miss Feisty) form the law-and-order backbone that pursues the Black Vipers, led by Kurogiri Ren — a villain bound by ancestral hatred.
Ancient diaries, a fate pendant made from a jade fragment, and buried chests reveal a prophecy: the Moon Tribe and a surviving bloodline will rise again. Betrayal, sacrifice, and clashes with shadow assassins build to a final confrontation where lineage and love decide the future. Justice is won, families are rebuilt, and a new generation promises life where there was once only ruin.