The twelfth episode of Dynamite Kiss commences with a poignant flashback as So-yeong humbly apologizes to both Da-rim and Ji-hyuk for the predicament she inadvertently created. Revealed is the fact that post her ex-husband's abandonment, So-yeong had applied to join the esteemed MotherTF team despite her qualifications being in order. However, despite her eligibility, she was inexplicably overlooked. While Ji-hyuk relishes in the resolution of this long-standing issue, Da-rim feels a burden of guilt for claiming a spot she believes So-yeong didn't deserve. Despite Ji-hyuk's attempts to alleviate her conscience, her demeanor remains unassuaged.
Cutting back to Ji-ye, she pays a visit to the MotherTF team with Da-rim's marriage certificate in hand. Initially, one might assume she confronts Da-rim over the matter, but instead, she and Tae-young hatch a more cunning plan – they aim to set a trap for Ji-hyuk, using Da-rim's secret to facilitate his ouster from the company. Ji-ye suggests a press conference as a means to clear the air, but Ji-hyuk resists, fearing it would only exacerbate So-yeong's mental anguish. Ultimately, they settle for a press release as a compromise. Later, Ji-hye reaches out to Tae-young, assuring him that Ji-hyuk is aware of Da-rim's single status due to his unwavering defense of her.
Meanwhile, the other teams extend their congratulations to Da-rim for being named Employee of the Month. The team pressurizes Ji-hyuk into joining them for a team dinner, which he gleefully accepts. However, Da-rim's guilt remains unabated, leading her to distance herself from the team.
Elsewhere, Ha-yeong embarkson a secret shopping spree with her mother in search of an appropriate outfit for Jun's event. She lies to her mother, claiming she's attending a friend's gathering. Speaking of Jun, he exhibits a hint of disappointment when Seon-u is tardy in picking him up. Nevertheless, his mood brightens when his father promises to practice songs together.
At home, Myeong-soon receives a call from her sister-in-law, inviting them over for a visit. Da-rim agrees to attend when an opportunity arises.
As the sun began to rise over the bustling office, Ji-hyuk remained behind, determined to unravel the truth of his investigation. His eyes landed on the recruitment files for the MotherTF team, and a chill ran down his spine as he realized that his sister had been playing a sinister game from the very start.
The next morning, Da-rim arrived early, her heart heavy as she sat down to write her resignation letter. She knew it would be a painful step, but she couldn't bear the charade any longer. However, Ji-hyuk refused to accept her resignation, revealing the nefarious plan hatched by Ji-hye. The truth dawned on Da-rim like a bolt of lightning—they had all been hired with the expectation that they would fail.
Ji-hyuk reminded her of how her unwavering determination had saved the team from certain doom. He referred to her as the heart of the team, urging her to stay until he secured permanent positions for all of them. Earlier in the day, he had met with both Ji-hye and Chang-ho, where Ji-hye had been clearly maneuvering them into a trap. Ji-hyuk had subtly hinted that he had seen through her scheme, making a promise to excel in exchange for his team's security.
Meanwhile, Jin-hee's eyes widened as she accidentally caught a glimpse of Ji-hyuk and Da-rim embracing. She shared her concerns with the rest of the team, who began to act awkwardly around Da-rim.
At Jun's school, Seon-u arrived late, missing an opportunity to perform with his son. But luckily, Ha-yeong stepped in to fill the gap, and Seon-u was slightly touched by their performance. However, later that day, he asked Ha-yeong to keep her distance, claiming he didn't want Jun to misunderstand and become attached only to have his heart broken.
The next morning, Tae-young stumbles upon Ji-hyuk in the office, attempting to provoke him with a taunting smile. However, Ji-hyuk swiftly disarms him with a cold stare, leaving Tae-young momentarily at a loss. Seeking reassurance on their plans' progress, Tae-young pays a visit to Ji-hye, reassuring her not to fret, despite the MotherTF team's impressive product idea.
Meanwhile, the team's behavior towards Da-rim becomes increasingly odd and suspicious. Finally, Da-rim confesses her secret to them, and to their surprise, the team embraces her relationship with Ji-hyuk. They forgive her for her lie, understanding her desire to save her family. At the team dinner, they tease Ji-hyuk after Gyeong-min shares their recent kiss in Jeju.
In the evening, Ji-hyuk and Da-rim head to his place. She apologizes for hurting him in the past by pretending to be married to Seon-u. Ji-hyuk brushes off her apologies, insisting that now that he knows the truth, everything is in the past. He promises not to let her go and asks her to stop running away from him. They end up making love and spending a weekend together, their bond strengthened by their shared experiences.
Meanwhile, In-ae tests the waters, secretly observing Myeong-soon's feelings towards Ji-hyuk for Da-rim. She is disappointed when Myeong-soon expresses her preference for Da-rim marrying someone from the same social class, dismissing Ji-hyuk's handsome appearance and status.
Elsewhere, Ha-young confesses her crush on Seon-u, insisting she won't marry an unthoughtful man like her father. Out of concern, Mi-ok visits Seon-u with the intention of paying him off but changes her mind after witnessing his care for her injured wrist. She leaves the money as a gift and returns home, the reality of her marriage dawning on her as Ji-tae insists she take care of him despite her injury.
The following week, the MotherTF team delves into researching various products and ultimately decide to update their baby carrier to make it less strenuous on parents' shoulders. Watching Da-rim in her element delights Ji-hyuk and makes him proud of her efforts. However, he also wishes he had more time with her, given their hectic schedules with the new product development.
After weeks of arduous work, the team receives the prototype of the carrier. As they proudly celebrate their achievement, Gyeong-min rushes in with a similar product from their competitor that was released that morning. Before they can process the shock, Chang-ho arrives and slaps Da-rim, his anger palpable in the tense moment.
