In the fourth episode of Resident Playbook, tensions run high as I-yeong, Sa-bi, and their colleagues continue to navigate the challenges of the hospital environment.

The episode kicks off with I-yeong’s sister visiting unexpectedly, leading to a moment where Sa-bi stumbles upon a message thread where I-yeong expresses doubts about continuing in medicine. This sparks Sa-bi’s concern for I-yeong, who seems to be hiding something deeper. Later, during a meeting with Professors Seo and Do-won, I-yeong is thrust into writing a paper, taking away an opportunity Sa-bi had been hoping for. Sa-bi’s disappointment is palpable, but she keeps her frustration to herself.

In a subplot, Nam-kyung, who’s struggling with a heavy workload, has an encounter with Dr. Myeong at a hair salon. After overhearing Nam-kyung venting about a nurse offloading tasks onto her, Dr. Myeong gives her a cryptic piece of advice on “revenge.”

Back at the hospital, I-yeong’s efforts to flirt with Do-won continue to fall flat. Meanwhile, I-yeong’s unexpected inclusion in a challenging case stirs up jealousy in Sa-bi, who goes as far as deleting I-yeong’s research files out of frustration. However, this only backfires when I-yeong is punished by being assigned to assist Professor Seo in every surgery—a task Sa-bi had secretly wanted. The dynamic between the two becomes more complicated as I-yeong’s hard work and dedication are put to the test.

As the case involving a pregnant woman whose baby is at risk progresses, I-yeong accidentally injures Do-won during a surgery, leading her to assist him in suturing. Meanwhile, Sa-bi’s envy grows as I-yeong is praised for her dedication. When the woman’s condition worsens, Sa-bi takes matters into her own hands again, removing a note from Professor Seo, only to regret it later.

Nam-kyung, on the other hand, starts reflecting on her actions. She realizes that the nurse she had been cold toward had actually been helpful and decides to be kinder, though her “revenge” plan continues in small ways. However, the nurse’s own revenge comes in the form of waking Nam-kyung up in the middle of the night for a seemingly petty task.

The emotional core of the episode lies in a painful procedure involving a stillborn child. I-yeong, initially hesitant to carry out the procedure alone, is encouraged by Do-won and eventually invites Sa-bi to assist her. Together, they manage to perform the task despite the heavy emotional toll. In a flashback, we learn that this procedure was a significant moment for I-yeong, as she had struggled with the decision to go through with it alone.

The episode ends with the characters growing and learning from their mistakes, but with lingering feelings of guilt, jealousy, and unresolved tensions between them, setting the stage for further emotional and professional development.