When John Barton's wife dies, he is forced to raise his daughter, Mary, alone, while he grieves the love of his life. Though he is a hard-working man, John struggles to provide for his family. Realizing how unfair his financial situation is, John becomes very resentful towards the unethical distribution of wealth between the social classes. Against John's wishes, when Mary comes of age, she decides to help support their family by working in a dressmaking factory. Neither John nor Mary are happy with the unsafe working conditions in the factory, but soon, Mary is presented with a way out when Henry Carson, the handsome son of a wealthy mill owner, takes an interest in her. Mary knows that marrying Henry would secure a comfortable life for her and her father, but she is conflicted when Jem Wilson, a respectful and hardworking man also declares his love for her. Though Mary reciprocates his feelings, she is conflicted. Mary rejects Jem and avoids Henry while she tries to decide whether to embrace her love for Jem or accept the financial comfort Henry would provide as a husband. While Jem respectfully accepts Mary's rejection, he decides to give her space. However, when someone warns him of the possible ill intent Henry has for Mary, he tries to defend her honor. After a fight between Jem and Henry is broken up by the police, Jem decides to spend time with his cousin, a sailor. But when a dead body is found soon after, and Jem becomes the prime suspect, Mary must solve the murder and leave home to help clear Jem's name before it's too late.

Set in Manchester, England, Mary Barton follows the Barton family as they witness and experience the hardships faced by Victorian working-class families, providing thoughtful insight on the social conditions of the 19th century. With murder, love, and discussions of serious social issues, Mary Barton depicts a powerful narrative that resonates even with modern audiences.