In the opening scene of The Art of Sarah's Episode 1, the launch party for Boudoir's 2024 Spring-Summer collection sets the stage for a mysterious tale. Regional head Sarah Kim, her voice echoing through the party, muses that truth, like the sun, blinds us, while lies, like a sunset, make everything appear beautiful—until they're exposed. A few days later, a Boudoir customer discovers a dead body in the sewers, seemingly Sarah Kim, dressed in her launch outfit. Her face is grotesquely disfigured, suggesting a brutal revenge. She froze to death days ago, clutching a luxurious purple bag and a partial print—a foot tattoo that reads "melancolie splendide."
Detective Hyeon Jae-hyeon joins the investigation alongside the team leader, Detective Park Mu-gyeong, who is initially annoyed by his youthful zeal. As they delve deeper, they uncover that Jeong Yeo-jin, CEO of Nox cosmetics, gave the bag to her close friend, Sarah. Upon arriving, Yeo-jin recognizes the victim from her tattoo and is shocked to learn of Sarah's tragic fate. Yeo-jin recounts Sarah's story, which began with a Birkin bag.
A flashback reveals Sarah storming into a department store with a suitcase full of cash, buying everything she touches. Yeo-jin, an intrigued customer, is fascinated by Sarah's carefree attitude. One day, Yeo-jin's eye catches a glimpse of Sarah's special-order red Birkin bag. Curious about Sarah's lavish lifestyle and success, Yeo-jin is later snubbed by a potential VIP client, Chairman Choi Chae-u, for being nouveau riche. As she storms off in a fit of rage, Sarah accidentally drops wine on her bag. Yeo-jin smacks her in anger but feels worse when Sarah simply apologizes and hands over her red Birkin as compensation. They grab a drink and learn that Sarah is a wealthy Korean American who attended Oxford University.
Their friendship blossoms as they become roommates and best friends, with Sarah teaching Yeo-jin how to be classy and out-of-the-box thinkers. She exploits weaknesses and plays hard to get until she has the other person begging to meet her—the opposite of what should be expected.
Present-day Detective Park Mu-gyeong believes the killer is sending a message by leaving the purple Birkin bag. He refuses to believe their friendship was genuine, but Yeo-jin insists it was. The investigation deepens as they try to unravel the mystery surrounding Sarah's death and the true motives behind this gruesome act.
In a flashback, Sarah reveals that Boudoir is venturing into the hotel business, and Yeo-jin eagerly expresses her desire to collaborate. However, Sarah dismisses Nox as a suitable partner, causing Yeo-jin's heart to ache. One day, Yeo-jin discovers that Sarah is secretly meeting with Choi Chae-u. Determined to outdo Choi, Yeo-jin insists on becoming an investor despite her board's concerns about the risk. She redefines her aesthetic and convinces Sarah to enter into a partnership.
However, it is Sarah who demands a 15 billion investment. Yeo-jin's friends are skeptical, but Boudoir quickly becomes a resounding success. Yeo-jin receives a 1.5 billion won dividend in the first month alone. The launch party marks the last time Yeo-jin sees Sarah alive.
Present day, Yeo-jin claims she didn't report Sarah missing because it wouldn't have made a difference. She also doesn't have any photos since Sarah didn't like taking them. As she leaves, Mu-gyeong notices the bag carelessly placed on the floor and wonders if it's fake or if the friendship was. She's perfectly poised, just like Sarah. To make matters worse, morgue CCTV footage shows Yeo-jin spitting on Sarah's dead body.
Mu-gyeong conducts a quick database search and discovers that Yeo-jin is under investigation for robbery-linked assault by the financial crimes unit. The FCU team leader reveals that Yeo-jin's lackey has been arrested for kidnapping, assault, and extortion. The lackey confesses that Yeo-jin wanted the 15 billion won back but Sarah refused.
A flashback shows that no money has come after that first month. A fearful Yeo-jin admits she's embezzled money for the investment, but Sarah simply scolds her for being impatient. Suspicious, Yeo-jin checks the red Birkin and discovers it's a fake. She then throws it in the river.
Meanwhile, the FCU leader shows Mu-gyeong CCTV footage of Woo Hyo-eun, a sales associate who was viciously beaten and injured. The FCU leader assumes that the suspect accidentally kidnapped her instead of Sarah. A flashback shows Woo Hyo-eun with bruises and a broken leg that she might have faked to resemble Sarah. At the precinct, Mu-gyeong gives her his tie to wipe her tears but comments on her crutch usage as she leaves.
Present day, Mu-gyeong realizes that Woo Hyo-eun might have been faking her injury and is actually Sarah. Furthermore, the suspect Min Byeong-kwan reveals that all the Boudoir bags he stole were fake. The episode ends with the Foreign Affairs Division revealing that there is no one called Sarah Kim from the US.
