Second year resident Kang Si Young working as a part-time doctor in prison. Meanwhile, former doctor Cha Yo Han, now a prisoner helps prisoners who are in need of medical treatments.

Inmate 5353 is known as a hypochondriac, but former doctor Cha Yo-Han does not believe so. Shi Young's mother and uncle try to talk her out of leaving for Madagascar. She wants to stay, but will she?

Inmate 5353's symptoms over the last few weeks, when stacked together form a diagnosis of a disease that only 0.00001% of the population has. Since the disease is hereditary, the doctors try to find a family member.

Park Jung BO, patient 5353, disappeared from his room after suffering a seizure that required him to be uncuffed. In a department meeting Min Tae Kyung as head of the anesthesiology department proposes to reinstate her daughter Shi Young.

Cha Yo Han has been reinstated as a doctor and the minister of health recommended him to the Hanse Hospital. A famous MMA fighter comes looses his vision during a fight and Yo Han helps him. The next day he's at the hospital.

The condition of MMA fighter Joo Hyung Woo gets worse. He stops breathing, but despite a DNR, Yo Han intubates him. Shi-young hears from Chae Eun-Jeong that the Yo Han's euthanasia patient of three years ago, wanted to live.

While Joo Hyung Woo is still unconscious his lawyer requests a hearing with the hospital board about his DNR. His wife agrees, but his father does not and the law does not recognize a DNR without an incurable disease.

After the long day Shi-young is invited by her uncle for dinner and drinks. Not knowing Yo Han is now her supervisor, he has invited him to join. Lee Yoo Joon and Kang Mi Rae appear to be living in the same apartment building.

Shi-young's father is in cardiac arrest after being in a coma for a year. It stirs up a lot of emotions in the Kang family owned hospital. The MMA fighter has thanked Doctor Yo Han in an interview and the next day the clinic is flooded.

The pain clinic, flooded with people, has two opposite and rare cases: CPRS and CIPA. Constant pain and no pain at all. Proscecutor Son Suk Ki visits the hospital, apparently for Yo Han, yet his conversation is with Shi-young.

The prosecutor and nurse Chae Eun Jung discuss the possible euthanasia that could be happening at the hospital that Yo Han is now working at. Lee Ki Suk seems to be cured from CIPA. Choi Seung Won has a herniated disc in his spine.

Lee Ki Suk does not want his phantom pains cured, as he will loose all touch senses again, but Yo Han shows manages to convince him. Shi-young learns that patient's stories can be of tremendous help in finding a diagnosis.

Yoo Joon shares his story about his sick father, who was on a death bed for ten years, with Mi Rae. Shi-young discovers Yo Han's secret and he asks her if she can handle it. He shows her how he lives and why she is not allowed to worry.

A shuttle bus full of patients arrives at the hospital. One patient is coughs a lot, has a 39.5 fever and complained about vomiting. This after just minutes before a warning came in about the deadly and highly contagious Nipah virus.

Yo Han wants to help the diagnostic process, but no one is allowed in the quarantined area. Until a mother of child with pediatric diabetes is worried about her daughter, since she hasn't had any food since breakfast.

Yi Moon calls a press conference to boast about Yo Han's miracle diagnosis, but it backfires as journalists start to ask about the euthanasia case. Prosecutor Son joins a group that talks about facing death and assisted suicide.

A journalist in contact with Chae Eun Jeong brings up the euthanasia case at the press conference. Lawyer Han Myeong-oh steps in and tells them to focus on the current events. The entire department of pain medicine gets all new equipment.

What Yo Han thought was just a temporary loss of balance has now developed into auditory distress and dizzy spells. He falls down the stairs several times, before Shi-young finds him and gets him away from the nosy reporter.

Shi-young takes over the presentation and the audience is impressed. Yo Han realizes he needs her help and is ready to accept it. The prosecutor is nosing around the conference figuring out how the company Zinmu Rijund ties into all this.

Shi-young picks up Yo Han to bring him to work, but instead he asks her to take him to his doctor: the results are in. The pain medicine team grants Yoo Ri Hye a wish and after some hesitation, she decides she wants to see her son.

Yo Han is the number one suspect for the assisted suicide attempt and both the detective and the prosecutor are the same as from three years ago. Yoo Joon is shocked but doesn't believe Yo Han would be that stupid.

Despite the DNR Yo Han tries to save Yoo Ri Hye. Only Mi Rae is willing to help him. Shi-young finds Min Sung, Ri Hye's son as he's run away from home to see his mom. The prosecutor investigates the security footage.

Prosecutor Son Suk Ki receives his first chemo therapy treatment for stomach cancer. His investigator calls to show him a video showing a terminal cancer patient's euthanasia. Shi-young and Yo Han visit Park Yung Bo at his job as barista.

When Cha Yo Han comes out of the hospital for his check up, prosecutor Son Suk Ki is brought in on the ambulance in terrible pain. Lee Ki Suk is back, but this time his prognosis is not good and he gets worse rather fast.

Seok Ki asks Yo Han how he can understand his patient's pain when he is a CIPA patient who can't feel any pain. Gi Seok opens his eyes, and he can answer Yo Han's question by blinking his eyes. Meanwhile, Eun Jeong exposes Yo Han's secret by writing it on the hospital's bulletin board.

Yo Han wants to treat Gi Seok, but the disciplinary committee decides to exclude him from all medical duties. To find out the reason why Gi Seok is sick, Yo Han goes to the warehouse where Gi Seok was bullied by other students. Meanwhile, Eun Jeong gets to know that Seok Ki is sick.

Tae Kyung thinks that it is not right to fire Yo Han. Ri Hye gets a strange text from Death Talks. Won Gil meets Yo Han and tells him about the Cherubim. However, Yo Han gets furious about the idea of the Cherubim, and he calls Seok Ki to report Won Gil.

It was Chan Seok, the sales manager of Zinmu Rijund, who injected the Cherubim to the members of Death Talks. Myung Oh and Chan Seok leave Korea after Won Gil's death. The patients who were treated by Yo Han come to the disciplinary committee to oppose the dismissal of Yo Han.

Chairman Yi Soo dies. Tae Kyung, Si Young, and Mi Rae mourn his death. Mi Rae decides to move back in with Si Young. Later, when she finds out that Yo Han was about to board a plane, she rushes to tell Si Young. Meanwhile, with the chairman's passing, Joo Kyung asks Tae Kyung to consider taking over his position.

Si Young can't reach Yo Han, and she is worried about him. However, Yo Han doesn't contact her for three years. After the three years, Yo Han finally comes back to the hospital and meets Si Young, but he doesn't explain what happened to him for the past three years.

Yo Han suggests Si Young that she should do a brainwave test on the patient. Si Young asks Yo Han why he didn't tell her that he was sick, and Yo Han apologizes to her. Yoo Joon tells Si Young that Yo Han kept watching Si Young for a year, and Yo Han and Si Young finally confirm their love.