In Siren's Kiss, Cha Woo-seok receives a mysterious call from an informant who claims to have evidence of a fraud-related murder. Before revealing the truth, the informant falls to her death. Woo-seok's investigation leads him to Royal Auction and its chief auctioneer, Han Seol-ah, whose three fiancés have all died under suspicious circumstances. To expose the truth, or perhaps to test her, Woo-seok proposes they fake a relationship. As he uncovers her secrets, he realizes he may have stepped into a web he can't escape—and that getting out could cost him everything.