The poor class president participates in the Burger Song Challenge to buy burgers for her friends.

Living in a group home, 17-year-old Park Seon dreams of becoming an actor. But she must leave and face life alone at 18. Caught between her reality and dream, Seon hears of a ‘wish-granting underpass.’

Mira in her late 40's has been living in Paris for around 20 years. Having just divorced her French husband, she decides to visit Korea, and meets her old friends Young-eun and Sung-woo. While having a cheerful time in the bar, Mira goes to the toilet and after she returns, time is reversed back to 19 years ago. It is the day of Mira’s farewell party, before she left to France.

Seon-ji and Jin-hee were friends but become sisters-in-law when Jin-hee marries Seon-ji’s older brother. As they prepare food for ancestral rites together, Seon-ji is bothered by the way Jin-hee treats her mother.

Young-seok, who feels overwhelmed and lonely in what should be his glorious youth, meets a woman who introduces herself as Josée, and they share a once-in-a-lifetime romance.

Pregnant Yoo-kyeong visits her in-laws' house with her husband Jae-hyeok to perform her father-in-law's first memorial service, and there, she begins to feel a strange sense of déjà vu.