Episode 4 of "Resident Playbook" kicks off with the residents deeply engrossed in their diverse projects, their concentration unbroken until I-yeong's sister makes an unexpected visit. However, in a moment of oversight, I-yeong leaves her laptop unmanned, its screen illuminating a conversation about her contemplating a career change away from medicine. This revelation sets off alarm bells in Sa-bi's mind, who watches with growing concern.
Later, during a pivotal meeting with Professors Seo and Do-won, I-yeong finds herself reluctantly tasked with writing a paper—an opportunity Sa-bi had been eagerly anticipating. Disappointment gnaws at Sa-bi, yet she remains composed, bottling up her frustration. Meanwhile, Nam-kyung takes a brief sojourn to a hair salon during a lull in her duties, where she happens upon Dr. Myeong. Catching wind of Nam-kyung's grievances about a nurse unloading tasks onto her, Dr. Myeong offers some intriguing advice on "taking revenge."
Returning to the hospital, I-yeong's attempts to charm Do-won continue to fall flat. Sa-bi then stumbles upon I-yeong diligently toiling over her latest project, but her spirits sink further when I-yeong is selected for a challenging case. This case involves a couple who had tragically lost a baby due to a heart condition and are now pregnant once again. Professor Seo is resolute in ensuring a healthy delivery, but the case's risks, given their past, are palpable.
Consumed by jealousy, Sa-bi succumbs to temptation and deletes I-yeong's crucial research files. The consequences are swift: I-yeong is reprimanded, but rather than being sidelined from the project, she is assigned to assist Professor Seo in every surgery—an irony that stings Sa-bi, who had yearned for such an opportunity. This turn of events backfires spectacularly on Sa-bi, whose frustration grows exponentially.
During a critical surgery, I-yeong inadvertently inflicted a slight wound upon Do-won, compelling her to lend a hand in the delicate task of suturing. Meanwhile, Nam-kyung sought to affirm her position by adopting a chilly demeanor towards the nurse who had previously exploited her good nature.
Later, as I-yeong sought to mend fences with Do-won, their conversation was abruptly halted by the arrival of an expectant couple. Diagnostic tests revealed a distressing picture: the mother's amniotic fluid was critically low, and an infection had infiltrated her uterus at just 20 weeks, rendering salvation for the fetus impossible.
Elsewhere, Professor Seo heaped praise upon I-yeong and slipped a note into her email, attaching pertinent documents. However, Sa-bi, in the throes of a downward spiral, snatched the note away, only to be seized by regret shortly thereafter. Upon returning to reclaim it, she found it missing, her guilt intensifying with each passing moment.
Concurrently, Nam-kyung found herself contemplating the actions of the very nurse she had coldly treated. Earlier, this same nurse had come to her aid in front of a professor, after a patient's sudden vomiting incident. The nurse had also cleared the area for the professor, affording Nam-kyung the privacy to change into fresh attire.
Acknowledging her error, Nam-kyung resolved to adopt a kinder demeanor, albeit secretly entrusting Jae-il to keep her minor "revenge" scheme under wraps. However, a twist emerged when the nurse retaliated by rousing Nam-kyung in the dead of night for a trivial task!
In another part of the hospital, I-yeong caught Sa-bi in the act of copying Professor Seo's note. Instead of confronting her, I-yeong extended an invitation for Sa-bi to assist in a heart-wrenching procedure: obtaining a tissue sample from the deceased fetus for DNA testing.
A flashback revealed that I-yeong had initially declined to perform the procedure solo but, bolstered by Do-won's encouragement, she included Sa-bi in the task. Despite the overwhelming emotional burden, the pair successfully executed the procedure, and the sample was dispatched for genetic analysis.
