Dong Joo is one of the interns who have joined Geodae Hospital recently. He is notorious among his seniors for disobeying and playing smart. Seo Jung 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.

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

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

Dong Joo comes to know that Master Kim is Dr. Boo Yong Joo 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 asks Dr. Song to check on Master Kim by using Dong Joo. Therefore, he heads to Doldam Hospital with In Beom.

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

Dr. Song passes a letter of appointment to Mr. Jang 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, Dong Joo and In Beom get into a fight and In Beom punches Dong Joo.

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

President Do comes to Doldam Hospital in order to explain himself to Chairman Shin. Seo Jung ends up running away after writing a letter of resignation, but Dong Joo eventually finds her. Seo Jung also gets a diagnosis that she does not suffer from PTSD, so she can happily return. Meanwhile, Ms. Woo 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 Dong Joo, so that he can bring Dong Joo over to his side. Master Kim comes to know about it, but tells Dong Joo to decide his future on his own. Meanwhile, Seo Jung comes to know about Master Kim’s pupil, Jang Hyun Joo through In Soo.

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

Seo Jung 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 Dong Joo decides to shut down the emergency room.

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

Hyun Jeong visits Doldam Hospital to stop Chairman Shin’s heart operation, but she gets shock after hearing Chairman Shin’s test results. Master Kim asks Chairman Shin to cancel the operation as he has terminal lung cancer. Meanwhile, Dong Joo and Seo Jung 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 Dong Joo helps him a lot by asking In Beom 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. Noh’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.