Kang Dongjoo is one of the interns who have joined Geodae Hospital recently. He is notorious among his seniors for disobeying and playing smart. Yoon Seojeong gives advice to him that as an intern, he should follow whatever he's told without thinking. She further explains that the intern should put an elephant into a fridge even if it seems impossible.

Seojeong suddenly disappears one day after the car accident. Meanwhile, Dr. Do asks Dongjoo to operate a VIP patient and tells him to take it as an opportunity. Dongjoo accepts it but fails. Later on, Dongjoo receives a personnel order and heads to Doldam Hospital in Jeongseon, and meets someone there.

Master Kim and Dongjoo operates on Seojeong’s wrist as she cuts herself. During the operation, Dongjoo gets shocked with Master Kim’s speed and tries to follow his speed. Meanwhile, Master Kim kicks out Seojeong since he thinks of her as a mentally disturbed patient.

Seojeong gets caught while treating a patient even though she was kicked out by Master Kim. Master Kim gets furious about it and Seojeong goes to beg for his mercy. Dongjoo gets angry after finding it out and goes to face Master Kim. Meanwhile, Chairman Shin Myeongho visits Doldam Hospital to meet Master Kim.

Dongjoo comes to know that Master Kim is Dr. Boo Yongjoo and tries to stay back at Doldam Hospital to learn things from him. Finally, he gets a chance to perform a combine operation with Master Kim. Meanwhile, President Do Yoonwan asks Dr. Song Hyeoncheol to check on Master Kim by using Dongjoo. Therefore, he heads to Doldam Hospital with Do Inbeom.

Dongjoo goes to have lunch with Geodae Hospital staffs and hears something bad about Master Kim. Meanwhile, an emergency patient arrives at Doldam Hospital and Seojeong decides to operate on him with Inbeom as there is no one who can take care of it.

Dr. Song passes a letter of appointment to Mr. Jang Gitae and tells him that he is now Manager Jang. By passing the letter, Dr. Song asks Manager Jang to reveal every secret of Doldam Hospital. Meanwhile, Dongjoo and Inbeom get into a fight and Inbeom punches Dongjoo.

An armed man holds Seojeong as a hostage and barges into the operating room. He yells at Master Kim to stop the surgery, but Master Kim continues the surgery until the end. Meanwhile, Ms. Ji from Geodae Hospital comes to know about Seojeong’s PTSD history.

President Do comes to Doldam Hospital in order to explain himself to Chairman Shin. Seojeong ends up running away after writing a letter of resignation, but Dongjoo eventually finds her. Seojeong also gets a diagnosis that she does not suffer from PTSD, so she can happily return. Meanwhile, Ms. Woo Yeonhwa seems to have a secret.

Doldam Hospital faces extreme times when a rear-end collision involving six vehicles occur. As the traffic accident patients flood in, Mr. Choi from Internal Affairs’ daughter is also involved in the accident. Mr. Choi tries to stop Master Kim from performing any medical practices despite his daughter’s life is on the line.

President Do suggests an incredible offer to Dongjoo, so that he can bring Dongjoo over to his side. Master Kim comes to know about it but tells Dongjoo to decide his future on his own. Meanwhile, Seojeong comes to know about Master Kim’s pupil, Jang Hyeonjoo, through Jeong Insoo.

Parents of deserter find Dongjoo and ask him about the cause of their son’s death. However, Dongjoo hesitates to answer their question at first place. Meanwhile, the daughter of the sepsis patient who passed away due to Dongjoo’s operation on a VIP visits Doldam Hospital and holds a demonstration against Dongjoo.

Seojeong tries her best to be the first assistant of Chairman Shin’s operation and with her ceaseless efforts, Master Kim appoints her as the first assistant. Meanwhile, three suspected patients of MERS visit emergency room of Doldam Hospital, and Dongjoo decides to shut down the emergency room.

Seojeong decides to treat the patients in the emergency room after Dongjoo faints. At the same time, Master Kim receives the results of MERS test. Meanwhile, Dongjoo gets well and decides to get a Christmas present for Seojeong.

Uhm Hyeonjeong visits Doldam Hospital to stop Chairman Shin’s heart operation, but she gets shocked after hearing Chairman Shin’s test results. Master Kim asks Chairman Shin to cancel the operation as he has terminal lung cancer. Meanwhile, Dongjoo and Seojeong act like an enemy as they don’t want other staffs to know about their relationship.

Master Kim decides to do Chairman Shin’s operation. Master Kim tries his best to reduce the surgical time and Dongjoo helps him a lot by asking Inbeom to join them. Meanwhile, President Do plans to visit Doldam Hospital and suggests two options to Master Kim as he couldn’t stop Master Kim from the operation.

Master Kim succeeds Chairman Shin’s operation with every Doldam Hospital staff’s help. However, even if the surgery was successful, Chairman Shin fails to wake up and President Do heads to Doldam Hospital. Meanwhile, Reporter Oh visits Master Kim and tells him that he would write an article about everything.

People start to gossip about Chairman Shin’s brain-dead condition on social network and President Do decides to take it as a great chance to shut Doldam Hospital down. Meanwhile, Reporter Oh calls Master Kim and asks him to reveal the truth about everything.

President Do publishes an article about Chairman Shin’s surgery without Master Kim’s name on it and invites the medical staff who participated in the operation. Meanwhile, Reporter Oh visits former nurse, Ms. No’s restaurant to find out about the truth.

President Do throws a punch at Master Kim as he was humiliated in front of people. President Do and Master Kim’s fight turns into a body battle and a giant ice sculpture falls on Master Kim’s body. Meanwhile, President Do visits Chairman Shin and beg for his help.

As Doldam Hospital suffers from a lack of doctors, Master Kim visits the main hospital to ask to send young doctors to him and runs into CS fellow Cha Eunjae and GS fellow Seo Woojin. Woojin is ostracized by other doctors because he had done whistleblowing on other doctors' corruption and malpractice. On the other hand, Eunjae always takes a tranquilizer before operations due to her operation fright.

Master Kim gets disappointed at Woojin and tells him to go back. But Woojin asks Master Kim for one more chance and Master Kim gives Woojin a week of grace period to prove himself. Meanwhile, an important figure comes into the emergency room of Doldam Hospital. Do Yoonwan, the chairman of the Geosan University Foundation figures out the news and begins to work out his scheme.

Master Kim chooses the extreme method to save Minister Ryu. After Master Kim manages to bring Minister Ryu back to life, Park Mingook starts doubting on Master Kim’s real intention and skills. After Mingook announces the Minister’s condition to press, Master Kim just doesn’t seem to care. Eunjae asks Woojin to attend the second surgery, but he refuses.

Mingook asks Woojin questions about the primary surgery that Master Kim operated, and Woojin hesitates to answer them. The director of Doldam Hospital comes back to the hospital and Yoon Ahreum greets him. Eunjae gets furious on Woojin for taking away her opportunity to be in the second operation with Mingook. And Doldam Hospital is on the verge of being sued for malpractice.

Friday is the busiest day as a lot of patients swarm in Doldam Hospital. Eunjae still finds it hard to perform surgical operations herself. A girl patient who suffers from drug poisoning because of her father's joint family suicidal attempt reminds Woojin of a painful memory from his childhood. And the staff of Doldam Hospital resents after hearing a rumor that there will be a new director.

Master Kim leads his team in saving two critical patients at the same time. Eunjae steps in to protect a woman from her abusive husband.

Mingook becomes determined to turn people away from Master Kim. A situation Eunjae tries to mitigate takes a turn for the worse.

Even in her final moments, a paramedic saves another's life. Woojin shows Eunjae his way of resetting the mind from worries.

Woojin looks into diagnoses for Master Kim's arm pain. A bus accident conjures up a regretful moment that haunts Mingook's conscience.

Ahreum protects a patient's rapekit from failing into wrong hands. Mingook finally brings up the bus accident from 11 years ago to Master Kim.

Mingook asserts his authority by restructuring the hospital staff. Woojin is stunned to learn which surgeon was behind a faulty operation.

A recruiter with bitter resentment for Woojin tries to tempt staff members to leave Doldam Hospital. Eunjae's mom asks for a favor.

Eunjae panics when she runs out of medication from Master Kim before surgery. Woojin gets coerced into leaving Doldam Hospital.

Master Kim tasks Woojin with a final assignment. Mingook performs surgery on a VIP patient despite pushback from Shim Hyejin.

Do Inbeom returns to Doldam Hospital to investigate an unsuccessful surgery. Mingook decides between his greed and the truth.

Bae Moonjeong comes clean to Woojin about the connection between their families. Master Kim secures a safe future for Doldam Hospital.

The medical staff of Doldam Hospital fly out in a helicopter to a ship lost out at sea on behalf of Master Kim, who is absent on vacation.

As the patient's lung condition deteriorates due to tuberculosis, Master Kim opens the trauma centre operating room for Ri Bokyoung's surgery.

Doldam Hospital hires new personnel. The people of Doldam, who thought Master Kim would be the new head of the trauma centre, hold an emergency meeting.

Patients injured in a residential fire are rushed into the emergency room. Seo Woojin treats the suspected arsonist despite Jang Donghwa's criticism.

Cha Jinman hates that Master Kim's methods are deeply rooted into Doldam Hospital and takes everyone except Lee Seonwoong and Donghwa to the trauma centre.

The trauma centre loses a patient and receives another patient in critical condition. Meanwhile, a child visits Master Kim at Doldam Hospital.

Wounded soldiers are rushed to Doldam Hospital. Yoon Ahreum is left alone to tend to the emergency room when rogue patients suddenly cause a scene.

Patients rush into the emergency room while the staff tends to surgeries. Doldam Hospital falls into chaos as the gunman's identity is revealed.

When an old building collapses resulting in several casualties, a disaster medical support team is dispatched to the site.

Doldam Hospital receives news of a second collapse, but the place is still full of injured people. Master Kim leaves everything and heads to the scene.

Go Gyeongsook does not give up the legal battle over her son's death. She proposes a secret deal to bring down Jinman, but Master Kim opposes to it.

Jinman fails to find the culprit who broke into the director's office. His reputation is further ruined as incidents from his past become known.

Kang Dongjoo returns to Doldam Hospital, with his unconventional proposals causing a stir in the trauma centre.

Eunjae performs emergency surgery on a non-trauma patient while she must join another surgery for a patient with multiple traumas.

People injured from a forest fire rush into Doldam Hospital. Yet, the trauma centre is empty due to the staff staging a boycott against Dongjoo.

A fire approaches as if it would devour Doldam Hospital at any moment. Only after evacuating all the patients do the staff realise Master Kim was gone.