“Everything is repeating.”
Legend of the Blue Sea has two parallel storylines, one set during the Joseon Era and the other in the modern world. A major theme of the show is history repeating itself and the desperate attempt to keep this from happening. In the Era timeline, the newly appointed townhead, Dam Ryeong, releases a mermaid who was captured by the local innkeeper back into the ocean. Before the mermaid, Se-hwa, swims away, she turns around and reaches her hand to Dam Ryeong, “which he briefly holds.” This connection sets off their intertwined destiny for both storylines.
In the present world, Joon-Jae is a conman, who works with Nam-Doo and Tae-oh. After completing a large con, the three separate on vacation, where Joon-Jae heads to a seaside resort. It is here, where mermaid, Shim-Cheong, is caught up in a tidal wave and washed ashore, and breaks into Joon-Jae’s hotel room. Despite Joon-Jae’s attempt to get rid of Cheong, she refuses to leave his side.