- “You are very handsome when you're angry.”
- ―Theresa to Diego
Theresa is a feisty, quick-witted and independent woman who thinks she can handle herself in any situation.
She is very cynical towards anyone who is a threat to her or her friends and she is sharp tounged when it comes to insulting someone.
Theresa is a very good singer and cook.
The New Order
Before he returns home, Sergeant Garcia (Henry Calvin) angers Theresa Modesto, a tamale vendor, when he tries to carry out the orders of the acting governor. Luis Rico (Frank Wilcox) has decided that all of the vendors must be removed from the plaza despite their objections, and Diego de la Vega (Guy Williams) promises Theresa he will try to help. She shows her appreciation with hugs and kisses, thereby angering her boyfriend, Joaquin Castenada (Perry Lopez), who was watching. Joaquin starts to say something to her but is knocked aside by Capitan Briones (Ric Ramon), leader of a band of soldiers named "Especials". The Especials have come to carry out Rico's orders and do not report to Garcia, who objects to their brutality. Joaquin tries to attack the soldiers but is stopped by Diego and Garcia, who know he would be killed. Briones arrests Theresa, and Bernardo (Gene Sheldon) must hit Joaquin with a mallet to keep him from sharing her fate. Diego tries to reason with Rico but he remains firm, for this is his first command and he wants an orderly city. He allows Diego to pay Theresa's fine and they head back to her stand. Joaquin has recovered and berates Diego for stopping him, but the Especials arrive again and the impetuous youth is arrested. Briones plans to beat him to death to teach the other peons a lesson and Zorro must free him. When darkness falls, Zorro sneaks into the fortress and tells Joaquin to insult the guards until they open his cell to discipline him. When they do, Zorro drops down on them and locks them inside, taking Joaquin into the hills to hide. The boy vows to return, and Zorro knows the matter is far from over.
An Eye for an Eye
Joaquin and several followers begin a series of raids against the Especials, which culminates with the beating of Capitan Briones. The soldier issues a death order for Joaquin and sends his men after Theresa, intending to force her to reveal his hiding place. She asks Diego to hide her, and with Garcia's assistance, he protects her from the searchers.
Zorro and the Flag of Truce
Briones puts Theresa in jail until Joaquin surrenders. Diego intervenes and arranges for her to carry the truce offer to Joaquin, offering to go along to help convince the outlaw to surrender. Diego and Theresa succeed, but later, as Joaquin rides into the pueblo, the soldiers are lying in wait. Just as they are about to kill Joaquin, Zorro spots the hidden soldiers and narrowly rushes the outlaw to safety. Rico and the Capitan tell the governor it was Joaquin who broke the truce, and the angry official orders the troops to capture the rebel dead or alive.
The broken truce has convinced Joaquin that Diego cannot be trusted and, that if not for Zorro, he would have been killed. When Diego and Bernardo ride to his camp to explain, the rebel leader orders his men to lock the visitors in leg irons until he can decide upon a suitable fate for them. Joaquin announces his plans to kill the governor (John Litel) the next day while he visits a local shrine, after Theresa dances for them. When he tries to ride there, however, Joaquin is accidentally captured by Sergeant Garcia.
The sergeant takes Joaquin and Theresa to Rico and the corrupt official decides to use the rebel to help him gain control. He tells Briones to escort Joaquin to the shrine, where the murder will be carried out. If Joaquin refuses, Theresa will die. Zorro, having freed himself and Bernardo, stops Joaquin just as he is about to kill the governor.
Hoping to make the two men settle their differences, Zorro puts them in leg irons and gives each of them the other man's key. He then rides to the jail to free Theresa, but Briones draws his sword and prepares for a fight. The governor and Joaquin arrive and order the battle stopped, for the truth has been told. Rico is shot while trying to escape and Briones is taken prisoner. The governor orders all charges against the rebels dropped and declares a fiesta to be held to celebrate the end of Rico's reign.