Much of the film takes place in her home state of Maryland. She returns there to rescue her family members from slavery. She aids a few of her relatives in escaping to Canada while taking her parents into her own home. She traveled back a few times to aid more of her family members, then branched out into aiding other slaves in their escape.
Harriet Tubman's actions were ones of bravery and courage of countering the unjust, alongside other abolitionists. The film gives some insight into how Harriet Tubman outsmarted slave masters, slave catchers, and taught other slaves (and escaped slaves) ways to escape on their own. Harriet Tubman is portrayed by the actress Cicely Tyson. Who also portrayed a former slave (although fictional) in the equally excellent film, The Autobiography of Miss Jane Pittman.
All in all, this film is definitely worth watching. You can get the full quality version on DVD here