Legend of the Blue Sea is inspired by a classic Joseon legend about a fisherman who captures and falls in love with a mermaid. It is a modern twist about a mermaid Shim Cheong (Jun Ji-hyun) who seeks her love with a con-artist Heo Joon-jae (Lee Min-ho). Their lives intertwined in the Joseon era and after reincarnation, meets again in the present age.