Juri, Yong-hee, Si-hyeon, Hyeong-jo, and Dong-min are all twenty-five years old when they meet at a call center. Each of them has dreams of a different future, but for now they need to earn a living while preparing for a proper job.
When they chose to work at a call center, they expected a physically comfortable job. What they failed to predict was the abusive callers, customers who shouted, made unreasonable demands, and hurled insults. Despite such stressful conditions, Si-hyeon’s earns a promotion to a specialist consultant. However, one customer constantly harasses her with insults and condescension. As the call continues, Si-hyeon experiences setbacks in life that pushes her past her limit. She decides to go to Busan where the customer lives and take her revenge. When Si-hyeon announces her plan, Dong-min, who has secretly been in love with her, decides to follow. Soon, Juri, Yong-hee, and Hyeong-jo join the journey as well.