Stephanie (Anna Kendrick) is a cheerful and optimistic single mother who also runs her own live broadcast channel. She often shares some of her life lessons on the Internet, and her original recipes are loved by fans. By chance, Stephanie met a woman named Emily (Blake Lively). Emily looked confident, rich, and glamorous. She lived in a luxurious villa with her husband Sean (Henry Golding), a university professor. Simple Stephanie quickly established a deep friendship with Emily, and the two became good friends who talked about everything. However, one day, Emily disappeared with Stephanie's son. When Sean, as her husband, could not provide any valuable help for his wife's disappearance, Stephanie decided to find the whereabouts of the two herself.