The Family Secret is an early film adaptation of a popular 19th century melodrama. The plot concerns the daughter of a wealthy man who has secretly married a man below her station of whom her father violently disapproves. The father, in an excess of parental concern, separates the lovers by sending his daughter away so that she might forget her inamorata, unaware of their married state; during this time, she gives birth to a daughter. After some months, the young mother returns to her family manor and presents her father with his new granddaughter, which causes a most unfortunate scene. Unbeknownst to the young woman, her enraged father falsely accuses his son-in-law of theft and has him incarcerated in order to separate the lovers in an irrational attempt to force his daughter to forget this "unworthy" young man.