How can a mermaid from the Joseon era survive in modern society? Shim Cheong is a mermaid who follows her one true love, a nobleman’s son named Kim Damryeong from the Joseon Dynasty, to modern-day Seoul. Damryeong’s modern doppelgänger is Heo Joonjae, a highly skilled scam artist who first becomes interested in Cheong because of a jade bracelet worth $6 million that Cheong wears. With nowhere to go, Cheong is taken in by Joonjae, who also finds his con partners, Jo Namdoo and Taeo, hiding out in his home from a vengeful past victim of their scams. Cheong discovers a rival for Joonjae’s heart in Cha Shia, a researcher at KAIST who deals with ancient artifacts. When a dangerous killer named Ma Daeyoung, sent by Joonjae’s stepmother who wants to make her own son the heir to Joonjae’s fortunes, can Cheong survive her strange new environment while also helping Joonjae avoid the dangers that await him?