Based on Isabelle Gibson Ziegler’s novel, Portola leads an expedition to San Diego, where Junipero Serra founds a mission and tries to convert a local tribe.
In 1769 Captain Gaspar de Portola (Anthony Quinn) travels in a coach through Mexico in a hurry, and a woman is hit by the horses. Father Junipero Serra (Michael Rennie) tells Portola that the woman is dead. Portola offers Serra a ride to Mexico City; but Serra says it is the rule of his order to walk even though he has a lame leg. Portola and Jose Mendoza (Richard Egan) leave a horse for Serra.
The governor shows Portola a map and tells him he will occupy land and be in command. They are looking for seven cities of gold. Mendoza mentions a battle, and Serra says he knows the story of how Cortes killed so many. The governor says that Serra is the spiritual director and is in charge of founding the mission. Portola says Serra is a cripple, and he does not want to be burdened by a man who is not physically fit; but Serra promises that he will not inconvenience him. Mendoza tells Serra not to pack so many trinkets, and Portola agrees with him and asks for Serra’s blessing. Serra prays for the company, and he warns them they are starting out as bad soldiers. He tells how a few soldiers stripped people of their land and their gold. He challenges them to remember that they are children of God. He asks them to burn it into their hearts. As they set out on horses, Portola tells Jose that Serra is some kind of man.
Portola sees a rockslide cover the trail, and then they see a few natives. Portola orders muskets, but Serra gets permission to approach them. He gives them strings of beads. Mendoza tells Portola he should have shown them gunfire. The natives step aside, and the Spaniards pass by a large group on the mountain. They stop and make camp. Serra thanks Portola and offers him some wine. Serra sits by Mendoza and shares the wine. Serra says he used faith as well as beads. They both remember Spain. A musician is shot with an arrow dead. Mendoza tells Portola they should have shot Indians as an example. Portola asks to see Serra’s leg, which is swollen. Portola says a litter will take him to a station. A muleteer tells Serra he would not let a mule go like that. Serra asks him to treat his leg as if he were a mule.
In the morning Serra shows Portola that his leg has been treated. He tells Mendoza he did it with beads. As they pass through a desert, Mendoza finds Serra picking a flower. Serra says it is undiscovered and asks him to name it. They are surrounded by natives. Mendoza shoots a hawk, and they run away. They find a canteen and try to find their way back to the column. They are caught in a wind storm. Serra sees a light and walks toward it. They reach a cabin, and an old man and a woman welcome them and give them water and food. The woman holds her baby. Mendoza and Serra fall asleep at the table. They wake up on the sand by a cactus. Mendoza says he dreamed they were given water and food in a house. Serra says there was a child, and he describes the man and the woman. As they start walking, they see three men with two extra horses.
They arrive at Rivera’s camp by San Diego. A soldier asks for the padre because there is a plague. Serra learns their chaplains are sick. Portola learns that sixty have died. Portola asks the captain to go back and get supplies by ship. Portola says Mendoza will have to remain there in command. Serra offers to be in charge of the mission. He puts a bell in a tree and sanctifies the ground as a mission. He tolls the bell and prays in the rain.
Portola says goodbye to his friend Mendoza and says he will get his share of any gold they find. Portola leads his men north. In the evening Mendoza hears natives making sounds like birds. They attack with bows and arrows. The Spaniards use cannons and guns. Serra helps by bandaging the wounded. The Indians retreat, and Mendoza carries a wounded Indian to Serra. The doctor treats his wound and tells Serra to tighten and release the tourniquet through the night.
In the morning the doctor says the bleeding has stopped. Serra tells the grandson of a chief that they can heal their wounded. Serra gives him a sling and says they are all brothers under the same God. Serra shows him how he uses scissors. Serra tells Matuwir (Jeffrey Hunter) to have them come. Mendoza is angry at Serra for letting him go.
Serra rides a horse to the native village. Matuwir tells him to go, but Serra says he came to speak to his grandfather. Serra says he came to be friends and to tell them of his God. They ask about scissors, and he gives them one. The grandfather says evil men came before, and he asks if he may keep the scissors. Serra says he may, and the grandfather says he can stay near the great waters. Serra says he will try to teach them about his God. He shows a doll to a woman, and he gives out ribbons. Matuwir gives the doll back and tells Serra he has to travel far. Serra asks him to come so that he can hear the sound of the bell.
Some women have come to the mission. Mendoza asks the name of the beautiful woman, and Serra says she is Ula (Rita Moreno). Drums are heard, and all the natives run toward them. One native tells Serra that Matuwir’s grandfather died, and Serra says he will come. Mendoza goes with Serra to the village. Matuwir asks Serra to make his magic. Serra says he must have the saving water and invites him to come to church. Matuwir tells Serra he wants to marry a mother and two daughters. Serra says it is not permitted. Matuwir sends away the mother. Serra says he can have only one. Matuwir chooses the pretty one.
Mendoza sees women playing in the surf, and he speaks to Ula. She asks how many wives he has, and he says he has none. They play, and he kisses her. She is surprised but likes it.
Portola returns with wounded men and says men starved to death. Portola says he did not find the bay of Monterrey. Portola fears the supply ship will not come, and so they will start back to Mexico in the morning. Mendoza says Serra has not yet converted one Indian. Serra does not want to leave the mission and prays. Mendoza visits Ula, who realizes they are leaving. She asks to go with him, but he says she is the sister of the chief. Serra asks to speak to Portola and says he ordered bells and that no supply ship with bells has ever been lost. He asks Portola to wait nine days, and he agrees.
Portola prepares their ship to carry their supplies. Matuwir brings his wife to learn from Serra. Ula tells Mendoza that it is arranged for her to go with him. Matuwir sees them kissing and says they will be married. Mendoza tells Ula that she would not get along with his people. He tells her to go back to her tribe. She realizes he does not want her and runs off. He runs after her. Backing up, she falls off a cliff to her death. Matuwir goes to her, tears off her beads, and carries her body.
At the mission Mendoza asks Serra if he is writing that he killed her. Mendoza admits he is proud and asks if he is a murderer. Mendoza is upset and breaks a cup. Serra hears the drums, and Portola says they are war drums. Serra suggests that he could flog Mendoza, but Portola refuses.
The next day Matuwir comes to the mission and tells Serra they came for Mendoza. Serra will not give him up. Matuwir says goodbye, and an arrow burns their flag. Matuwir leaves with his escort, and war drums are heard. Portola orders Mendoza to go to the church and stay there.
In the evening an Indian jumps a guard and cuts open their water bags. In the morning Portola looks at the lost water. He says there are thirty skins of water on the San Carlos ship. He sends some men, but then they notice that the San Carlos is on fire. Serra says they have twelve more hours. Soldiers tell Serra that they are turning over Mendoza, but Serra says he has sanctuary. Serra grabs the leader’s gun and throws it down, and they go back. Portola tells Serra to give the men communion in the morning because they are going to attack.
In the morning the men are given guns. Portola gives orders. Serra gives the men communion outside. Mendoza kneels and prays that he may do penance to amend his life. Serra gives him bread. Mendoza walks out the gate. Later Serra returns with the body of Mendoza draped over his horse. Serra tells the doctor that they cut out his heart. He directs where the body is to be buried. Serra prays and cries.
The flag is lowered. Serra pours the last of the holy water on flowers, and they leave. Serra says he is leaving the bell because he has not given up. Matuwir and his tribe watch them go. On the way Portola sends a man to take a bearing from the hill, and he sees the San Antonio ship in the harbor. Portola says they are going back. He sees Serra kneeling in prayer.
Supplies are being unloaded on the beach. More bells are brought for Serra, who says they are for the mission at Monterrey. He says they will name a greater harbor to the north for Saint Francis. He says he can hear them coming.
This historical drama is based on facts regarding Portola and Serra but includes a fictional story involving Mendoza and the local tribe. The spiritual work of the great missionary Serra is portrayed in the first mission he founded at San Diego. As usual the Spaniards’ greed for gold and lust for women caused problems. The following year Serra would found a mission at Monterrey.