While attending school in Madrid (and receiving fencing lessons on the side), Tessa Alvarado learns of her father's death and leaves immediately for her hacienda in California. Upon arriving, she discovers her father had been murdered and the peons starving because of the policies of the local tyrant with the connivance of the wealthy landowners. In a dream, she is visited by the ghost of her father who encourages her to seek justice for the oppressed and avenge his death. Through her servant's tarot cards, Tessa discovers it is her fate to use her skill as a fencer ...
The Queen of Swords is shot while investigating reports that her villagers are being abducted and men sent to Colonel Montoya's prison are never seen again. In spite of her wound, she continues her search and discovers the men being forced to labor as slaves in Montoya's secret gold mine.
An epidemic strikes Tessa's village and the surrounding countryside. When Colonel Montoya is stricken by the fever, Captain Grisham takes advantage of the situation by stealing or destroying Dr. Helm's entire supply of medicine, and blames the Queen of Swords for the theft. Tessa turns the tables on the officer by drugging his drink with herbs that cause fever-like symptoms and, as the Queen of Swords, follows the Captain where he hid the stolen pills.
When Don Aguilera is shot, his son assumes the would-be assassin is Don Fuentes since he recently had a violent argument with the young man's father. The Queen of Swords intercepts the assassin sneaking into Dr. Helm's surgery and discovers the intended victim was the doctor, not the don. While Dr. Helm is spurning the Queen's offer of help, the would-be assassin strikes a deal with Colonel Montoya to help each other rid themselves of their adversaries.
While trying to protect a deserter who offered to name her father's murderers, Tessa is forced to reveal the hiding place of a young Indian shaman trying to retrieve a gold mask stolen from his father's burial site. The Queen of Swords manages to rescue both men, but the deserter decides it would be more profitable to reveal the Queen's identity to Colonel Montoya rather than provide Tessa with the information she has already paid for.