After marathon runner Suji's twin sister, Korea's top celebrity, passes away in an accident, Suji loses the light in her life; Suji gives up running to work part-time jobs.

The ten girls come to 825 Entertainment, ready to become idols, but Shinhyuk makes an unexpected announcement -- the girls have just one week to prepare for a mock test; they must figure out how to work as a team despite barely knowing each other.

The girls face an unexpected dance battle, after which the loser must clean the dance studio; Suji shocks the girls as she feels the rhythm and dances her best; Youngjoo notices that Suji has talent, causing jealousy and tension to sprout.

The day for the girls to show their performances to the world arrives; everyone looks forward to the broadcast, but the comment section only talks about the relationship between Suji and Suah, making the other girls green with envy.