In the opening of Episode 10 of Siren's Kiss, Seol-ah and Woo-seok unexpectedly bump into each other at Hyun-su's residence. Seol-ah curtly informs Woo-seok that the property is registered under Chairwoman Kim's name, but does not divulge further information, coldly pushing him away. As Woo-seok departs, he discovers evidence that the artwork was temporarily stored at that location. He installs a GPS tracker on Hyun-su's car. A flashback reveals Woo-seok bidding farewell to his sister and later receiving the call about her demise.
The detectives now turn their attention to Eun-hye. They inquire about her motive for following Jun-beom and Seol-ah, and she explains that she wanted to uncover Seol-ah's intentions. Eun-hye also confesses to recording the video of Seol-ah and Yun-ji's argument. The police also question Suk-ji about her presence at the auction house's event, where she claims she thought it would be a good opportunity to meet eligible bachelors. She also informs the police that she noticed Yun-ji stalking Seol-ah and even swapping out her decaf beverage. That's why Suk-ji confronted Yun-ji during the auction, on the staircase, and warned her to stop meddling with Seol-ah.
At the insurance company, Woo-seok shares with the others that Hyun-su and Han Seo-yul (the driver who crashed the Taemyung paintings) are living together and were likely involved in the scheme together. They then learn that Jun-beom has left the Stiller painting to Seol-ah. However, since Jun-beom was actually Su-ho living under a different identity, the ownership can be contested.
At the police station, Joo-young asks Eun-hye why she has such a strong dislike for Seol-ah. Eun-hye reveals that she initially liked her but changed her opinion as she witnessed Seol-ah using her brother, Eun-hyuk. Eun-hyuk overhears all of Eun-hye's harsh sentiments and later apologizes to her.
Later on, Seol-ah is enjoying a drink with Suk-ji and Eun-hyuk, thanking them for always supporting her. Eun-hyuk and Seol-ah discuss their relationship a bit, and Seol-ah admits that she thought Eun-hyuk was keeping a distance from her because he didn't want to be more than friends. She says she dated Su-ho because he had even less than she did. Regarding the others, Seol-ah states that she didn't want to be alone.
Meanwhile, the detectives begin to suspect Eun-hyuk. Joo-young questions him about his whereabouts at the time of Su-ho's murder, and he agrees to provide her with his dash cam footage, which proves that he was at his studio in Cheongun.
At work, Seol-ah trains Sang-mi to take over her position. She then receives a call informing her about the Stiller. Woo-seok meets her under the guise of discussing the Stiller but actually wants her to know that he's worried about her. Seol-ah still thinks he's in danger, but he says he still wants to be by her side and asks her to protect him. They end up working together.
Seol-ah speculates that Hyun-su is Chairwoman Kim's henchman. They now realize that the real painting must be stored at the chairwoman's vault at Felix Storage. At the same time, Chairwoman Kim meets with Hyun-su and tells him to move the paintings to her vault. As they're having lunch together, they are joined by another person whose identity remains a mystery.
Seol-ah and Woo-seok go to Felix Storage to investigate but by then, Hyun-su has already moved the paintings. While driving back, they share their respective pasts. They then meet Dr. Shin (Woo-seok's contact, a hacker), who finds the auction house's architectural blueprints. Through the plans, they discover the location of Chairwoman Kim's vault.
The next day, Chairwoman Kim happily greets Seol-ah since she is the new owner of the Stiller. However, Seol-ah says she has no intention of accepting it. Chairwoman Kim then reveals that she will replace the Stiller (in the auction) with a painting made by a late artist named Song Hwan-ju.
That evening, Seol-ah places a bug on Kim's car. When the chairwoman leaves, Seol-ah goes up to her office and finds the secret vault. She gains access since she knows the chairwoman only ever uses one password for all her devices.
Once inside, Seol-ah loses connection with Woo-seok. Unfortunately, Chairwoman Kim receives a notification about someone accessing her vault and asks her driver to turn the car around. Dr. Shin sees this, but he and Woo-seok can't get in touch with Seol-ah anymore. Upstairs, Seol-ah sees one of her father's paintings. A flashback shows her father teaching her how to paint and then painting that scene itself.
At present, Seol-ah can't leave the vault since it requires a different passcode to exit. Kim gets into an elevator as Woo-seok rushes to get to Seol-ah. Seol-ah is still inside when someone opens the door.
