The Movie Begins showing pictures and films of the actual victims Of Rafael Trujillo.
During the montage a title card appears that says:
- From 1930 until 1961, General Leonidas Trujillo held absolute control of the Dominican Republic.
- His secret alliance with the church, aristocrats, intellectuals and the press were the foundation of his dictatorship.
- His formula to remain in power was simple: murder anyone who opposed him.
- More than 30,000 thousand people were executed during his regime of terror...
The scene shifts to inside of a prison cell where one of his victims, Minerva Mirabal recounts the events of the story.
Minerva and her three sisters Patria, Dede and Maria Teresa ("Mate") live on a farm in rural Ojo De Agua. Minerva, the outspoken sister, convinces her father to send her, Patria and Mate away to attend school. The sisters spend five years away at school, during which time Minerva captures the attention of el Jefe (Trujillo), who notices Minerva at a school play.
When school is over, Minerva wishes to study to become a lawyer, but women are not allowed in law school. So the sisters return to the farm, and Minerva soon meets and falls in love with Virgilio ("Lio") a member of the resistance, who gives her the nickname "Butterfly". Lio's activities during a college protest are noticed, and he is forced to leave the country out of fear for his life, though he continues to write to Minerva.
Minerva, along with her family, is invited to a formal ball at the President's palace, where she dances with Trujillo. During their dance, Minerva asks for permission to attend law school, but Trujillo declines. He touches Minerva inappropriately, and she responds by recoiling and slapping him in the face. Her family quickly rushes to her side, and Trujillo allows them to leave.
The next day the police arrive at the family farm and take Minerva's father away. The sisters spend several weeks dealing with the police bureaucracy trying to locate their father before it is suggested that there is a way that Minerva can get her father out of prison. Minerva goes to the palace and Trujillo suggests that her father can leave if she stays at the palace. Minerva points out that her mother is waiting outside and would "appreciate his hospitality" too. Trujillo decides that that they should leave it to chance (a dice roll), to determine if Minerva and her family go free, or if Minerva stays at the place while her family is free. Minerva accepts, but asks to "up the stakes" - if she wins, she goes free and also gets to attend law school, and if she loses, Trujillo can "have his wish". She rolls the dice and wins, and Trujillo lets her leave.
Minerva's victory is hollow. Her father is released from prison, but has been tortured, is not well, and soon dies. While attending his funeral, the police chief delivers to Minerva a letter permitting her to attend law school. Minerva's hatred of Trujillo is intense, but she decides to accept his "gift" to attend law school because she views it as her only way to effectively oppose Trujillo.
While in law school, Minerva discovers that Lio has been killed by Trujillo supporters even though he was out of the country. She meets other members of the resistance, who through Lio, know of her as "Butterfly". She becomes a member of the resistance, and over time Patria and Mate learn of her activities and become involved too. She falls in love with Manolo, a fellow law student and member of the resistance, and they are married.
When Minerva graduates from law school, Trujillo is present to pass out the diplomas. All the other students receive diplomas, but he refuses to give Minerva a diploma saying he agreed to allow her to attend law school, not to practice law.
After law school, Minerva has children, but continues her resistance activities. After a series of increasingly dangerous events she, Mate, and many resistance members are arrested and sent to jail. Minerva becomes a symbol, and many prisoners, guards, and outsiders secretly voice their support for "the Butterflies".
Eventually Minerva and Mate are released from jail, but their husbands and Patria's are still held captive. The women continue their efforts to locate their husbands and inquire about their status. Trujillo stops by to visit Minerva at her home, and she asks for his help to get their husbands released. Trujillo vows to help Minerva "end her troubles".
While returning from a trip to visit their husbands, Minerva, Patria and Mate are stopped on the road by a large group of Trujillo's men. They are taken some distance off the main road, and the men surround them and beat them to death.
Another title card appears at the end that says:
- The Death Of The Mirabal Sisters was the final blow to the regime of Leonidas Trujillo, who was assassinated six months later.
- Several of the children of the Mirabal sisters held important posts in the later democratic governments of the Dominican Republic.
- The day of the sisters' death, November 25, is observed in many Latin American countries as the International Day Against Violence Towards Women.