The first episode of The Unit is titled ‘The Reboot’. The performers who have not gotten enough chances to show their true talents even after their debut, challenge once more to make their dreams come true. As the top-class mentors appear, the contenders’ stages that will surprise them begin.

Two of the former girl group members, Han Areum and Yang Jiwon, get reappraised while getting the most attention on the stage. Areum left her group after suffering from a rumor while she was in a popular girl group. And Jiwon has been working part-time and goes to audition to audition since her group was disbanded. Meanwhile, the 13-year-old girl, Lee Juhyeon’s talent and her phenomenal dance skill get highly praised by the mentors.

The mentors sympathize with Mad Town’s story in which they have continued to dream and practice even after they lost the support of their agency. Although MVP claims that they are confident with their unified group dance, their first performance disappoints the mentors. Yet, the mentors change their minds after seeing MVP’s amazing second performance. Meanwhile, Joo comes up on the stage and everyone is surprised just to hear her name.

A friend who had dreamt together with Hyuna as a young trainee, Joo gets on the stage which makes Hyuna become surged up with emotions. Hyuna roots for Joo as she watches her perform in full of joy. Hotshot’s Timoteo tells a story of his friendship with Taemin after he gives his performance. Taemin who has been remaining calm eventually bursts out tears. Meanwhile, Marco from H.B.Y captivates everyone with his outstanding talent and unique charms.

As the booting evaluation is coming to an end, female teams with various charms appear. A group of talented vocalists, Matilda makes the mentors laugh with their cheerful energy. Rubber Soul’s Kim gets noticed as one of the strongest performers with her outstanding rapping and singing. H.U.B’s Hyosun captivates everyone with her charisma as soon as she shows up on the stage.

The contestants who have passed the first round gather in a mysterious place in the order from the ones who received one boot to the super boot. Rain gives them a mission to form groups on their own to compete for a 500,000 dollars-worth music video. While everyone else is overwhelmed and flustered, Serri from Dalshabet and Timoteo from Hotshot think on their feet and start to pick up strong members for their teams.

All the contestants move into the training camp and start practicing the choreography for the music video in each group. While some groups show off their great chemistry, the others run into problems as things get more challenging. Even with all the hard work they put in, some members make mistakes on the stage and receive tough criticism from the mentors.

With a surprise interim evaluation, the real front-runners start to reveal. Although everyone is paying attention to the female Black Team and male Red Team, they fail terribly at the interim evaluation. On the contrary, the groups that have not stood out before, bring good games and get positive reviews from the mentors which make the other contenders nervous.

The first hurdle where performers drop starts at last. Before they form groups, everyone gathers for fierce dance battles which to decide the best dancers of all. After this, each person goes into a room that has the title of the song they want to perform to. With the new group members, they start practicing in earnest.

Female groups take the stage for the restart mission. The unit makers start their voting as they watch the performances. And the first and last place are announced as soon as the performers get off the stage. The keen performances to survive begin of which everyone practiced all night as if it’s their last chance on the stage.

Through hardships, The Unit finishes all the performances and gets emotional as the winning female and male teams are announced. After going through a tough practice, the two winning teams and the mentor, Rain’s joint-performance is revealed.

Position Battle to decide the best performer of each position begins and everyone works hard to present their talent for 30 seconds to become the last one standing. After that, the performers are visited by the mentors and get to take courage and comfort from the mentors' advice and by opening up about themselves. Meanwhile, Park Narae and Kim Jimin visit The Unit as hosts of the program, 'Crying Fist', to help them with unresolved feelings.

As the male performers join ‘Crying Fist’, things get more heated and shocking truth are revealed with expose and counterattack. After that, the official announcement of the vote results commences. The moment of happiness by the announcement of the top nine performers only lasts for so long until the leaders of each group have to go back to their practice room to inform the ones who must go home. Everyone lumps the first farewell as they burst out into tears.

The Self-Producing Mission finally begins that everyone must decide on choosing the song, outfit, and choreography on their own. The groups are formed into three categories, which are vocal, vocal and rap, and performance, to compete with the rival groups. Everyone is more cautious about their moves and the male Team Yellow and Green’s performances begin.

Through careful planning and practice, most groups successfully present their performances after the behind stories are revealed. Some of the groups that followed the mentor, Rain’s advice from the interim evaluation, come up with amazing performances while Timoteo gets a negative feedback about the song he strongly pushed to the team as a leader. In spite of Rain’s advice to reconsider the song choice, Timoteo’s team sticks to the original song and takes the stage.

The performances for Self-producing mission of the female groups in the vocal and the dance parts begin. Team Yellow chooses an unexpected song, ‘Jackpot’ and surprises everyone including the mentors. Team Black’s Haein takes the charge of the choreography in her team and becomes highly praised for her extraordinary talent and taste.

The last groups for Self-producing mission take the stage and the announcement of the rankings follow. As the surprising results of rankings continue, everyone keeps themselves on their toes. And the male Team Orange gives a tearful performance with the rap song that is close to the members’ hearts.

The third mission, Album Production Mission, as well as the huge benefit and the chance to be on a music video from it, are revealed, which everyone can't help but be excited about. Soon, the opportunity to form their own groups is given to those from who placed the first to the fifth from the last self-producing mission. Meanwhile, as the ratings from the second official voting are announced, some of the performers burst into tears after an unexpected candidate for the ninth place of Unit G is nominated.

The result of the second official voting is revealed as well as the twist of Unit G's ninth place. In addition, an audition is held for the new centers and the members to take the dance break of ‘My Turn’ for the performances at Song Festival and Drama Awards. After the announcement of the ratings, the time to say goodbye to those who have to leave the Unit nears.

After the five songs for the mission are revealed, each leader of Unit B's groups competes to get the best song including the addictive "Mine". Sungjun of Team White appeals to every songwriter and makes everyone laugh. Meanwhile, Unit B's Team Green stays with Jungha who has injured his leg and gives their all to pull off the performance together.

Since Kijung of Team White takes an important part of the group, he is torn about how he can't hit high notes with the change of voice due to puberty. Yet, the members' heartfelt encouragement helps him overcome and keep going. Lee Geon and Daewon of Madtown get to perform in Team Orange and give a meaningful performance together despite hardships. Finally, the winner of Album Production Mission of Unit B gets revealed.

The announcement of Unit B's rating from the last voting surprises everyone. Finally, the new songs for Unit G are revealed and the leaders of each group compete to get the best-suited song for them. As Team Orange practices the song with a cute concept, "Poco a Poco", the older members struggle. Meanwhile, Team Yellow also endures with the pain of practicing in high heels.

Even though Team Green has great dancers, they have a hard time adjusting to the sexy choreography and lose the trust in the choreographer, Hwayeong. To earn her trust again, Team Green has to complete a mission to memorize the choreographies of all five songs including of other groups in three days. Meanwhile, Team white fails to get the song they initially wanted, “Poco a Poco” but manages to give a successful performance with “Always”.

After the 120-day journey, the third announcement that will decide the 36 idols out of 64 who will remain to perform for the final is set in motion. Due to the benefit from the last mission, it gets harder to anticipate the result of ratings. Meanwhile, Unit G appears on a radio show as well as Unit B on “Gag Concert” for a chance to promote a song each.

The eighteenth places, which will make the last members of Unit G and Unit B for the final, are announced. Another sad farewell comes and the new songs for the final stage are revealed to the remaining 36 idols. Each idol decides on the first to the third choice of whom they want to be teamed with as well as the song they want. The teams are formed based on their choices. As mini-missions, each team comes up with their own choreography and makes a short video.

Prior to the final stage, the journey of The Unit so far and the first interviews of them are shown. To thank the mentor, Jo Hyunah, members of Unit G prepare a surprise candid camera. And finally, the remaining 18 performers of Unit G’s special final performances begin.

Followed by Unit G, the remaining 18 members of the Unit B's performances begin. Before the final stage, the performers are greeted by the video messages from their beloved families. After they watch the video, they spend a quality time with their family members who show up by surprise. Once the final performances of each group are finished, the final nine members of Unit G and of Unit B are revealed.