Episode 1 of "Who Is She?" kicks off with a harrowing scene of Mal-soon, her face etched with panic, dashing into a restroom. The narrative swiftly transitions to reveal that Mal-soon's enterprising son-in-law, Choi Min-seok, has once again bitten the dust with his latest venture. Consequently, the family has been compelled to relocate back under Mal-soon's roof, much to the chagrin of her daughter, Ban Ji-sook, whose relationship with her mother is fraught with tension.
Meanwhile, Mal-soon's granddaughter, Choi Ha-na, clandestinely sneaks out to hone her musical prowess, shirking her academic responsibilities in pursuit of her passion. Elsewhere, we encounter CEO Daniel Han at UNIS' glittering fiesta, where he unveils a fledgling girl group with the intention of bowing out gracefully once they achieve fame. However, the group's central figure, Emily, vanishes, plunging Daniel into a perilous predicament.
Mal-soon, a single parent who has valiantly supported herself and her daughter by helming a thriving soup restaurant, is poised to hand over the reins to a duo of brothers. Yet, she is steadfast in her conviction that they must uphold the establishment's high standards. Later, she reconvenes with Ha-na at a karaoke bar, where she indulges in her forsaken passion for singing, a hobby she relinquished in the arduous task of nurturing her daughter and managing her restaurant.
The following day, amidst a breakfast table fraught with tension as Ji-sook scorns her mother for her perceived lack of empathy during her upbringing, Mal-soon reconnects with her sole confidant, Park Gab-young. Together, they partake in workshops tailored for senior citizens before Mal-soon embarks on an audition journey at UNIS. This is the culminating moment she has tirelessly prepared for, intertwined with her enduring rivalry with Kim Ae-sim, a celebrated singer who now chairs UNIS.
Mal-soon embarks on her performance but stumbles, unable to reach the soaring notes. Ae-sim, recognizing her rival, taunts her, asserting that stardom is not meant for everyone. Devastated and ridiculed, Mal-soon retreats to her abode to find Ha-na declaring her intent to forgo university. When Mal-soon attempts to lend support, Ji-sook erupts in fury, urging her mother to vacate the premises. Mal-soon, gathering her belongings in a daze, exits the house. A taxi driver offers her refuge in his cab, and she drifts into slumber during the journey.
Upon awakening, Mal-soon finds herself in a photography studio, with the taxi driver now portraying a photographer. Using an antique camera, he captures her essence. To her astonishment, upon opening her eyes, she beholds the miraculous transformation into her vibrant 21-year-old self!
