Jae-Rin seems like a hip college girl, but she spends her days as a shut-in geeking over Hwi, the male lead of her favorite period drama “Hwaya.”

As part of a family intervention, her sister talks her into accepting a job as a TV extra. Upon arrival, Jae-Rin discovers that the set is for “Hwaya” but ruins the takes with her awkward moveme...