Cha Young Min, the genius cardiothoracic surgeon at Eunsang University Medical Center, runs into Ko Seung Tak, a resident, on Seung Tak’s first day at the hospital. Young Min right away senses that it’s impossible for them to get along, so he comes up with a plan to remove him from his sight. Just when Young Min thought everything was going according to his plan, his plan backfires.

After the accident, Young Min is still confused about whether he is dead or alive but realizes that his body is in a critical condition. With time running out, Young Min must do something to save himself. One thing certain is that his spiritual self can become one with Seung Tak’s body and his body only. And then someone called Tes shows up calling him a coma ghost.

Nothing that has recently taken place was a coincidence, including both Chairman Jang’s critical condition and Young Min’s accident. Young Min’s job now is to find out who’s doing the dirty work for Seung Won. Young Min strongly believes Seung Tak is one of them, but then again, he thinks otherwise when Seung Tak makes a sacrifice for him.

With an emergency patient in front of him, Seung Tak struggles. At the same time, Young Min faces the risk of disappearing for good. The two become physically and mentally inseparable, but neither one seems to accept the situation. Meanwhile, Young Min finds out who the wrongdoer behind Chairman Jang’s case is and gets shocked.

Seung Tak has no other option but to ask Young Min for help in saving an emergency patient. While Young Min is impressed with his good faith, he is also shocked and realizes that there is a possibility that Seung Tak might be seeing him. But first things first, the two team up to save the patient.

Young Min finds out from the ghost patient that the accident he was involved in was also planned out by someone. Meanwhile, Seung Jo begs Seung Tak to do whatever it takes to save him. However, the only doctor who can save Seung Jo is Young Min, and the only person who can connect the two is Seung Tak.

Young Min is excited that he can save someone’s life again. At the same time, Seung Tak asks Young Min what it’s like to save a life all on your own. Meanwhile, someone special to Young Min visits the hospital, not as a guest but as a patient.

Young Min openly shares the secret of what happened 12 years ago, and at the same time, Seung Tak shares his side of the story regarding Young Min’s cardiac tamponade surgery in order to end the contract between the two. However, after hearing Young Min out, Seung Tak reconsiders the whole situation again. On that very night, Chairman Jang finally makes up his mind as the motorcycle patient regains consciousness.

Young Min and Seung Tak continue to save patients, and while doing so, they find out about Young Min’s improved condition. At the same time, Se Jin is confused when she repeatedly gets this feeling of Young Min’s presence from Seung Tak. Meanwhile, Seung Won begins to suspect Seung Tak for his odd behaviour after finding out that he’s been secretly performing surgery.

Young Min, while still inside Seung Tak’s body, can’t find the reason to hide his identity to a pathetic guy like Seung Won and surprises him with the unbelievable truth. Seung Won is shocked, but he gets hold of himself right away. Meanwhile, Young Min gets a chance to be alone with Se Jin thanks to Seung Tak. However, when he returns, he realizes that things don’t look too good at the hospital.

Young Min feels helpless when the coordination with Seung Jo goes wrong during surgery. Knowing how frustrated Young Min is, Seung Tak look for other ways to save him. Meanwhile, Se Jin tries to keep a distance from Seung Tak, and Seung Tak is bothered by her sudden change in attitude. After pushing Seung Tak away, Se Jin is alone, and that’s when Min Ho barges in.

Young Min loses his temper when Seung Tak tells Se Jin the truth about Young Min’s presence. Se Jin ignores Seung Tak’s nonsense, but she warns him to stay away from Young Min. After the incident, Young Min asks Seung Tak a favor regarding Se Jin. Meanwhile, Seung Won prepares Tae Hyun for another plot.

Seung Tak faces his worst nightmare and loses control when his surgery goes wrong. Just like that, he disappears. With Seung Tak gone, everyone at the hospital is worried, but at the same time, Young Min learns about Seung Tak’s tragic past. Meanwhile, as Seung Tak’s weirdness continues, Se Jin cannot help but suspect Seung Tak’s identity.

The link that connects the relationships among Young Min, Seung Tak, and Tes is finally revealed, and Young Min and Seung Tak now realize that they are meant to be partners. After putting the traumatic event behind him, Seung Tak returns and continues on with his life at the hospital. For Se Jin, it feels completely different to see Seung Tak in his best condition.

Se Jin is now aware of the secret that Seung Tak has been keeping from everyone. With Se Jin added to the crew, they face a new problem regarding their fair share of time with Seung Tak’s body. Meanwhile, Young Min focuses on saving more patients. It’s earlier than what Young Min and Seung Tak had expected, but they are running out of time, and Young Min needs to make the call.

Seung Tak and Young Min get ready for Young Min’s surgery, but Young Min looks like he has a lot on his mind. Either way, this is going to be their last surgery together as one. After the surgery, everyone waits to see if Young Min recovers. However, not everyone wishes that he would wake up or remember what has happened in the past few months.