In 1980s South Korea, Ko Yeong Rye works as a bus conductor at Cheong A Transportation, helping passengers get where they need to go. Although she has motion sickness, she's committed to her job to support her family. She's soon joined by Seo Jong Hui, a young woman with an impressively loud voice who also decides to become a bus conductor. Yeong Rye and Jong Hui become fast friends, but their bond is soon tested by Han Jae Pil, an aspiring boxer from a troubled yet wealthy family who bursts into their lives when he helps the two girls stop a fare evader. Yeong Rye develops a crush on Jae Pil, but Jae Pil seems to have feelings for Jong Hui, straining the friendship between the two. Will Yeong Rye and Jong Hui find a way to keep their friendship together, despite conflicting romantic pursuits?