365: Repeat the Year - Season 1

Hyeong Ju, while living an ordinary detective life, loses one of his closest colleagues, which in turn takes away all his motivations to live. This is when he receives a phone call from an unknown caller telling him that he can go back a year in time as long as he is willing to do so. Hyeong Ju decides to take his chance of traveling back in time to save his colleague. 

The first group of people to go back in time is selected and the reset becomes the reality. Hyeong Ju finds himself back in time before when Sun Ho is murdered. Ga Hyeon also is back to when she had two healthy legs. However, at the first meeting after the reset, they hear about the death of one of the group members who participated in the reset. 

What seemed to be a free opportunity for a better life sends Ga Hyeon into a downward spiral when she finds her friend, Ju Young, as the victim of exactly the same accident that she got into. Ga Hyeon then immediately seeks Lee Shin's help to see if there is a chance to undo what has already happened to Ju Young. 

After losing Ju Young from exactly the same accident as hers before the reset, Ga Hyeon decides to find the driver who killed her friend. While doing so, she gets this feeling where Lee Shin seems quite familiar with the recent series of happenings. Just when Ga Hyeon and Hyeong Ju were on the verge of finding the evidence, they come across the murderer, not alive but dead.

The police find the dead body of Yeon Soo at the park where she met with Ga Hyeon on the night before. When Ga Hyeon is summoned to be questioned as a testifier, she has no choice but to hide the details regarding the reset. Missing puzzles in between Ga Hyeon's testimony leave the detective in doubt, but in the end, an alibi that makes it impossible for Ga Hyeon to be the murderer gets confirmed. 

After the investigation at the police station, Ga Hyeon helps Hyeong Ju track down Bae Jung Tae, who might hold the key to recent mysterious deaths of fellow resetters. Although they are yet to locate Bae Jung Tae's whereabouts, Ga Hyeon finds something weird about Lee Shin's phone number at Bae Jung Tae's place. 

Ga Hyeon and Hyeong Ju eventually get in touch with Jung Tae and in doing so, they find out his relationship with Jeung Seok. However, as more they look into the mysterious deaths of the resetters, the clues somehow direct them toward Lee Shin. Ga Hyeon, in the end, decides to visit Lee Shin just to find out she has left the country. 

Ga Hyeon and Hyeong Ju are certain that Jung Tae is the bad guy and Jeung Seok is just one of his many victims. However, this all flips around when they come across a conversation between Jung Tae and Jeung Seok. In the meantime, Jeung Seok is found dead and Lee Shin calls all the remaining resetters for a meeting. 

When the resetters gathered at the meeting organized by Lee Shin, they get a basket of flowers with a memo pointing to the next target. Ga Hyeon and Hyeong Ju then search for the flower shop that made the exact flower basket like the one delivered to them. As they get closer to finding the answer, an unexpected clue stumbles upon them. 

Ga Hyeon and Hyeong Ju stumble upon So Hye In, the pregnant lady from the meeting before the reset who decided not to travel back in time. It turns out that the bouquets were made and sent from Hye In's flower shop. Ga Hyeon and Hyeong Ju ask her to contact them if she gets the same order. Eventually, Hye In gets another order of the same bouquet.

It turns out that the bouquets were sent by Ms. Song under Lee Shin's order but when Ga Hyeon and Hyeong Ju found out about it, Lee Shin was already gone. Meanwhile, what was thought to be an arson was just a mere accident at the flower shop. Moreover, Hyeong Ju finds out that Park Young Gil, the first resetter who died in a car accident, has a twin brother.

Ga Hyeon and Hyeong Ju finally figure out the true meaning behind the message, the date of death. However, this time, no one dies on the date they expected. After several months of peace, a case of a drowned truck driver surfaces. It turns out that the driver had died on the same date Hyeong Ju had in mind. 

Lee Shin shows herself at the café where the resetters were discussing the dead truck driver. This is when Lee Shin reveals the fact that the resetters were all dead in previous resets until she decided to save them on her sixth reset and to invite them all on her seventh reset. On the next day, Ga Hyeon hears from Se Rin that she's going to be the next victim of a gruesome death. However, it turns out that Se Rin was a liar all along. 

As suggested by Lee Shin, Se Rin tries to flee from Seoul with Young Woong. However, Young Woong leaves Se Rin at the bus terminal to meet Hyeong Ju to file a suit against her. Meanwhile, Jung Tae, who was also one of the victims of Se Rin's lies, gets parole and visits his sister who recently underwent heart transplant surgery. As the resetters start to lose trust in Se Rin, she desperately asks for help, saying that she will be the next victim. 

Ga Hyeon struggles to decide whether to help Se Rin or to ignore her for her deceitful wrong doings. Even before she had time to make a decision, Se Rin is found dead. Hyeong Ju and Ga Hyeon sort out Young Woong and Jung Tae as key suspects, but it turns out that their alibis are legitimate. Meanwhile, Jung Tae makes another deal with Lee Shin. 

It was no surprise when Hyeong Ju finds out Jae Young was with Se Rin hours before she was murdered. Meanwhile, Jung Tae is threatened by Jae Young's father, a nominee for the Minister of Education, to stay low until the hearing is over. While Ga Hyeon being confused by a series of puzzling events, Jung Tae faces a death threat by an unexpected acquaintance.

While Hyeong Ju is acting suspiciously for some reason, a voice recording is delivered to Seoul Makang Police Station as well as to Mr. Hwang and Ga Hyeon. This triggers Ga Hyeon to investigate the voice recording, and she eventually concludes that Hyeong Ju could actually be the culprit. However, her speculation is proven wrong when she faces a threat from the real culprit. 

Hyeong Ju feels irritated that Ga Hyeon suspected him of the murder of Jung Tae. Meanwhile, Sun Ho asks Hyeong Ju to explain certain things he's been having a hard time understanding. When he does, Sun Ho says he will believe him. However, later that night, Jae Young gets blackmailed by a stranger, and not knowing what or who is waiting for him, he decides to solve the matter on his own. 

Sun Ho turns out to be the murderer who caused the deaths of resetters. However, Hyeong Ju does not have a clue about it and reports every detail of his investigation to him. With Hyeong Ju under his watch, Sun Ho sets up a trap to falsely charge Hyeong Ju for the murders. While Hyeong Ju is on the run, Sun Ho visits Ga Hyeon for his next move. 

Putting the pieces of a puzzle together, Ga Hyeon finds out who the real culprit is and successfully confirms his identity. When Hyeong Ju hears her speculation, he refuses to accept that the real culprit is Sun Ho and storms out of his hideout. Hyeong Ju then retraces his memories and does an additional investigation to confirm Ga Hyeon's reasoning. Meanwhile, Sun Ho unexpectedly shows up at Ga Hyeon's house. 

Hyeong Ju and Ga Hyeon find out that Sun Ho is the real culprit who is responsible for the deaths of resetters. In fact, they also realize that Ga Hyeon's house is wiretapped by Sun Ho. Hyeong Ju understands that this is an opportunity to reveal the true identity of Sun Ho, and he sets up a trap to lure him.

Luring Sun Ho into Hyeong Ju's trap was easy, and the police arrest him right after he fires a gun at Hyeong Ju. It seemed as if everything was over, but Hyeong Ju discovers that Hwang No Sub has been lying and hiding his identity all this time. When he and Ga Hyeon visit him, people there greet them as if they expected the visit.

It turns out Professor Hwang was using Lee Shin for his pleasure through the reset. After finding out about his scheme, Lee Shin struggles to decide whether to help Ga Hyeon and Hyeong Ju or to once again go through the reset to avoid her daughter's death. Meanwhile, Ga Hyeon and Hyeong Ju realize Professor Hwang was behind the reset and attempt to stop him. 

Attempting to stop Professor Hwang from making use of the reset for his personal enjoyment, Hyeong Ju dives into his second reset with the help of Lee Shin. Even with the prevailing uncertainty, Hyeong Ju successfully takes control of the reset and carries on with his pursuit to stop Professor Hwang once and for all.