Nayoung, a newlywed bride, looks forward to welcoming her husband back home after working overnight as a police detective. But she comes home only to learn he had been murdered. Unable to trust the police, she takes matters into her own hands to uncover the truth. Too bad for them, though. Nayoung turns out to be a former North Korean spy and notorious elite assassin known to intelligence agencies by the code name "Tarantula." How will the Tarantula avenge her husband's death?