A county magistrate's plan to release mermaids into the ocean backfires when they're caught by fisherman.

Sometime during August, 1598, newly appointed governor Dam Ryung (Lee Min-Ho) stays for a night at an inn run by Mr. Yang (Sung Dong-Il). During that evening, Mr. Yang shows Dam Ryung a captured mermaid named Sim Chung (Gianna Jun). Later that night, Dam Ryung releases her into the ocean and, before she swims away, Sim Chung reaches out her hand to Dam Ryung which he briefly holds.

In the present day, Joon-Jae (Lee Min-Ho) is a smooth talking conman with magician like abilities. He works with Nam-Doo (Lee Hee-Joon) and Tae-O (Shin Won-Ho). For their next score, Joon-Jae impersonates a prosecutor and swindles a large amount of money from a wealthy suspect's mother. Joon-Jae then travels abroad and stays at an oceanside resort. Meanwhile, Sim Chung is swept up in a tidal wave and washed ashore near the oceanside resort. She sees Joon-Jae.