"Mother Tongue" is the story of a high-profile relationship between an Academy Award-winning actress (Josie Ho) and her much-younger partner, who has yet to find his true career path. The actress had a baby when she was very young, a daughter whom she was forced to give away because she wasn't financially independent and wanted her little girl to have a better life. But now that she's older, she realizes that it's time to find her long-lost daughter, now in her twenties, and hires a detective to find her. The mystery of what happened to her provides the film's drama and tension; also, the actress' partner doesn't know about her search--and the urgency and distraction of the search begins to erode their relationship, until he suspects that she's having an affair. By the end, the actress reunites with her daughter and salvages her marriage.