The ninth episode of Taxi Driver Season 3 commences with the Rainbow Taxi crew going about their daily routine, with Do-gi at the helm, as usual. As he idles by the bus stop, his eyes catch a glimpse of Ro-mi, a pre-debut idol. In a fit of nostalgia, he plays a Girls’ Generation tune inside the taxi, which catches Ro-mi's attention. She hails Do-gi's cab, requests a drop at the Han River bridge, and jumps into the river as soon as the Rainbow Taxi drives away. Realizing something is amiss, Do-gi makes a swift U-turn and without hesitation dives into the river to save Ro-mi, eventually bringing her to the hospital.
Back at the Rainbow Taxi headquarters, Do-gi informs his team about Ro-mi's predicament. The hospital calls to inform him that Ro-mi is safe and under observation. He then shows the team Ro-mi's suicide note, proclaiming her to be their next client.
At the hospital, Ro-mi's manager insists she is fit to leave, forcing her to return to her dorm with him. But Ro-mi resists, and Manager Song slaps and threatens her. Out of nowhere, Do-gi appears in the hospital parking lot. He runs Manager Song over with his car and whisks Ro-mi away to a safe haven.
A flashback reveals two high schoolers, Ro-mi and Ji-an, receiving a call from an entertainment agency about an audition. Their successful audition with Yellowstar Entertainment lands them a spot in the pre-debut girl group, Elements. CEO Kang Ju-ri of Yellowstar tells them they must drop out of high school, urging them to discuss it with their parents. Ro-mi's mother, a karaoke parlour owner, refuses to let her daughter quit school. Ro-mi defies her mother and flees to join Yellowstar Entertainment.
As they peruse the hefty fees in their contract, CEO Kang assures them that the fees will only be payable once they debut and start earning their own money. Ro-mi and Ji-an sign their contracts and are introduced to the other three members of Elements. CEO Kang then tasks Manager Song and General Manager Jeong Gyeong-su with escorting the girls to their dorm rooms, announcing Ro-mi as the group's leader due to her age.
At the dormitory, Gyeong-su and Manager Song employ the "good cop, bad cop" strategy to exert control over the girls. It proves effective, as the girls are captivated by Gyeong-su's charming demeanor, agreeing to abide by all the stringent rules imposed by him. Meanwhile, Producer Lee admonishes them for gaining weight, adding to their already arduous training schedule that sees them practicing day and night in preparation for their debut. CEO Kang presents the five trainees with their introductory video, painting a rosy picture of their bright future.
One night, Manager Song takes Ro-mi to see CEO Kang but spikes her water with a drug. The next morning, Ro-mi awakens in a mysterious room with no recollection of the previous night's events. She returns to the company, sharing her amnesia with CEO Kang, Gyeong-su, and Manager Song. Manager Song falsely claims Ro-mi had run out of the car, while CEO Kang blames her for her carelessness, causing her to panic and lose confidence.
A few days later, Gyeong-su shows Ro-mi and CEO Kang a video of her passed out on a nightclub table that he found online. CEO Kang urges Ro-mi to reflect on her actions and their potential impact on her fellow members, blaming her for not only ruining her own career but also that of the entire group. In private, Gyeong-su promises to help Ro-mi and wins her trust. He then asks her to return to the same club where the video was filmed, claiming the person who recorded it would be waiting there. Ro-mi accepts the offer, hoping to convince the man to delete the video if she gives him what he wants.
That night, Ro-mi goes to the club and enters the empty room but hesitates. In a moment of despair, she decides to end her life by jumping into the river. Coincidentally, Do-gi finds her at that moment.
Fast forward to the present day, the Rainbow Taxi team devises strategies to infiltrate the entertainment company. They use a fake warrant to seize the company's files. Go-eun discovers the video of Ro-mi passed out on a table and realizes that it shows Gyeong-su's reflection in the ice bucket. The team concludes that the trainees were being manipulated by the agency itself, and Do-gi volunteers to act as an inside man to expose them.
Just as Manager Song emerged from the hospital following the initial hit-and-run incident, Do-gi careens his taxi into him a second time. Gyeong-su informs CEO Kang of Manager Song's continued hospital stay, prompting them to embark on a quest for a replacement. Do-gi steps into the fray, disguising himself as a potential hire and impressing CEO Kang with his charisma.
Hired and tasked with instilling discipline among the members, Do-gi oversees their diet, interactions, and every move with an iron fist. He provokes Gyeong-su deliberately, stirring up trouble.
Do-gi grants Go-eun access to CEO Kang's laptop, where she uncovers the members' contracts. CEO Kang instructs Do-gi to drive the members to their next schedule while keeping a close eye on him, reminding him that he serves Yellowstar Entertainment, not the girls' well-being.
The bug in the pen hinders communication between Go-eun and Do-gi. That night, Jin-eon aids in de-bugging the pen, and they delve into Go-eun's discoveries from the laptop. Go-eun reveals that the contracts Ro-mi and the other members signed are essentially slave contracts, with exorbitant fees charged for training and mentorship.
Do-gi recalls witnessing CEO Kang physically and emotionally abusing the girls and Gyeong-su ordering a single roll of gimbap for them to share as dinner. He informs the team that the company was not searching for Ro-mi but actively preventing her from reaching out to the other members.
Jin-eon and Kyung-koo follow Gyeong-su to the building where Ro-mi was found, while Do-gi heads to the establishment where CEO Kang is having dinner with Producer Lee. A sudden noise disrupts their meal, prompting CEO Kang to search for its source. She enters the room where Do-gi is hiding, coming face to face with him as the episode draws to a dramatic conclusion.
