Episode 5 of "The Potato Lab" kicks off with Baek-ho dashing out to lend Mi-kyung a helping hand at the greenhouse. After their exertions, they retreat indoors for a soothing hot shower and some much-needed rest. Mi-kyung teases about joining him in the shower, but her growling stomach wins out, leading them to sit down together to enjoy a meal.
During their repast, Baek-ho discovers the depth of Mi-kyung's fervent dedication to potatoes. He finds her unwavering passion intriguing and labels her as "interesting," due to her relentless commitment to her work. This revelation prompts Baek-ho to ponder over his decision regarding her future with the team as the night progresses.
Back at the guesthouse, the arrival of Yoon Hee-jin leaves Hwan-kyung and Ong-ju utterly puzzled. They speculate about her connection to Baek-ho and conclude that she must be the director's girlfriend. When Ong-ju expresses her concerns to Mi-kyung, she initially brushes it off, but it's evident that she too is curious about the situation.
Ong-ju and Mi-kyung end up eavesdropping on Hee-jin, but she catches them peering through the window and promptly dashes over, excitedly inviting them all to her welcome party that evening. The gathering is a delightful grilled BBQ hosted by Hee-jin. While Hwan-kyung and Hee-jin hit it off, Mi-kyung tries to probe into the nature of Hee-jin and Baek-ho's relationship.
Convinced that they are high school sweethearts, Mi-kyung gives Baek-ho the silent treatment. However, this misunderstanding is swiftly cleared up when Hee-jin inquires about Baek-ho's romantic interests, subtly hinting at his feelings for someone. Meanwhile, it transpires that Ki-se has been keeping tabs on Hee-jin all along and has her followed. Specifically, he learns of her presence at the guesthouse.
The narrative shifts slightly as the team is briefed at work about the PMI Task Force. Ki-se takes center stage and announces that he will be leading the initiative, much to Mi-kyung's chagrin. His ulterior motive becomes apparent, and he sees this as an opportunity for her to advance, given that he can override Baek-ho's decisions. Mi-kyung is far from pleased and is further irked when Ki-se admits that he feels sorry for her and wonders why she hasn't progressed further in her career.
Just as Mi-kyung is poised to hurl a shoe at him, Baek-ho makes a dramatic entrance, and the duo's subsequent awkward behavior hints at some untold tension simmering between them. This underlying animosity spills over into their lunch, where Mi-kyung boldly declares her lips as Baek-ho's possession, much to the astonishment of everyone else in the vicinity who can only gaze in bewilderment.
Baek-ho, convinced that a ghost is haunting him thanks to Mi-kyung and her brother's antics at the Guesthouse, becomes increasingly paranoid. He records a high-pitched groan but to no avail as the duo feign ignorance, claiming they hear nothing. Adding fuel to his paranoia, Baek-ho notices red splashes on the floor of his office and his chair emitting a peculiar squeaky noise—the very same sound that has haunted his nights. Unbeknownst to him, the Potato Gang, who have been sneaking into his office weekly, are behind this mischief. One of them, engrossed in painting her nails, accidentally spills polish everywhere and breaks his chair in the process.
Yet, the group decides to keep quiet, leaving Baek-ho to descend further into a whirlwind of paranoia and anxiety. Desperate for answers, he seeks solace in a shaman's prayer, much to the astonishment of Mi-kyung and the others who realize their prank has crossed a line. Mi-kyung finally confesses that the eerie sounds are merely the chirping of white thrushes, but Baek-ho is far from pleased. No apologies or free gifts from Mi-kyung can assuage his anger. He brushes aside her every gesture, leading Ong-ju to aptly describe their dynamic as "doormats for each other" amidst their burgeoning romance.
Meanwhile, CEO Yoon confronts Ki-se about canceling Hee-jin's card, with tensions still running high between them. In a slip of the tongue, Yoon reveals that Baek-ho is in Pyeongwon, where his best friend also resides. When Ki-se arrives, he's taken aback to find Mi-kyung there, setting the stage for a dramatic turn in their complex relationships.
