A preschooler named Antonio Márez lives in a small town in the middle of the vast plains of New Mexico. His family are simple people: his mother Maria is a daughter of the farmers and now a housewife. She is very religious and sees the ideal career for her son for her son as a priest. His father, Gabriel, is a former vaquero (cowboy). He wants the boy to inherit his profession.
Antonio is very curious for his age, but what really differentiates him from the other kids his age is his interest in fundamental questions about the world and one’s destiny. In his six years, he already transforms the argues of his parents to the question if he has a prescribed fate or can choose anything he wants to in his life.
Some of this questions get answered when a powerful old woman (Europeans, probably, would call her a witch) named Ultima knocks at the door of their house. Ultima is a curandera or a supernatural healer. She is an old woman with a tamed owl on her shoulder. Despite her powers, she is also a herbalist and a skilled medic. She uses her powers for good to fight against the actual evil witches (brujas), but still she is a person who should be respected and feared. Ultima says to Gabriel and Maria that she is tired and wants to stay and live with them the last years of her life. Despite her religion Maria allows Ultima in and lets her stay out of deep gratitude - when she gave birth to Antonio, Ultima was her midwife. Maria thinks that Ultima is the only one who saw the true fate of her son.
Ultima is interested in Antonio and the little boy is charmed by her wisdom. She gathers healing herbs with the boy and answers his growing numbers of questions about God, world, nature and humanity. But his happy childhood is disturbed when he first sees the death of a man with his very eyes. It is Lupito, a World War II veteran with a heavy PTSD. He kills the local sheriff while having an especially heavy flashback and a mob is gathered to capture him. Lupito is still aggressive and dangerous, so one of the mob shots him to death. This event frightens Antonio but doesn’t traumatize him. Instead the boy starts to think about the nature of sin. Was Lupito a sinner, a mentally ill man or just a victim of his own fate? Where was God at that time and will God punish his own, Antonio’s, father for being in the mob also? What happened to Lupito after his death?
Next morning after that event Ultima takes the boy to the church and they have a long talk. Antonio asks her about fate and the old woman replies that everyone has to make his own choice, lots of them. Adjusting the moral compass and deciding what is good and what is evil will give the person the instruments to understand the world and their place in this world. Ultima’s words help Antonio more than the priest’s or those he heard in his family after Lupito’s death. Later she helps him to battle his growing fears and concerns, explaining to the boy her ways and the knowledge she received from her ancestors. Ultima never indoctrinates anything in him, letting Antonio decide instead.
She tells him a lot about both his father’s and mother’s lineage, weaving the answers to boy’s questions with ancestral legends and stories. Ultima shows him another way to treat the world around: her own wise and gentle attitude to the nature, her familiarity and the gift of a healer erode Antonio’s belief in single Christian god. He starts to doubt the religion Mary constantly told him about and asks himself if there are any other gods, gods of nature.
The war finally ends and Antonio’s older brothers, who were enlisted as soldiers before, return home. Gabriel celebrates this event not only because he is ready to see his sons alive. It also means that the whole family can finally move to the richer California as he planned long ago. But Antonio’s brothers are too traumatized by the war to live their previous lives. They willingly isolate themselves from the community and are clearly not enjoying staying in their family home. After some time of quarrels they finally leave to start their independent lives elsewhere. Antonio is left to see his parents’ sorrow and his brother’s pain. He tries to understand the origins of this family conflict, but can’t do that because he is too inexperienced to grasp the concept of a war trauma. When he asks Mary, she tells the boy that he will understand later, when he will take Communion. This promise makes him wait impatiently and anxiously for that time and even temporarily returns his interest to the church teachings and dogmas.
But his beliefs are shaken again when his friend, Samuel, calls him to go fishing and tells him about the powerful and benevolent god who looks like a huge golden carp and looks over humanity. This legend can’t combine with Christian faith, but it is perfectly acceptable in the worldview of Ultima. Antonio feels that her teachings explain much more in the life around him and answer more his questions than the church. Later he goes to visit the poor home of a town drunkard named Narciso and sees that Narciso lives a miserable life, dependant on alcohol and unable to stop drinking and reform. Another Antonio’s friend, Cico later tells him that if people won’t stop sinning like Narciso the golden carp will make a great flood that will drown all the humanity. Antonio solemnly wishes for a god of forgiveness coming to existence. He tries to finally join Christianity and Ultima’s beliefs, seeing Virgin Mary as goddess of forgiveness.
Ultima continues to treat Antonio as her apprentice. In the fall, before he starts school, Mary, worried with the changes she sees in her son, demands Ultima to reveal Antonio’s fate. She doesn’t want to do that at first but after long hesitation sadly says that he will dedicate his life to learning. Contempt, Mary returns to her daily duties. Her brother and Antonio’s uncle Lucas help the family harvest the crops and for some time they all enjoy common work and the evenings together. But once, Lucas falls ill and the strange illness progresses very rapidly. It looks more like of supernatural origins: neither the doctor nor the priest can do anything with it more than slowing down it a bit. Mary, who believed that the priest’s faith will cure Lucas, now has no other option than to ask Ultima for help. The old woman gathers the ingredients needed and starts the ritual.
It looks very horrifying, like in a story about demonic possession. The dolls around start moving like if they were alive. Lucas himself cries in pain, twists and spews bile, but finally exhausted Ultima defeats whatever was in him. She confirms the suspicions about the supernatural origin of the illness: according to Ultima it’s a witch’s curse. Soon she manages to find the one guilty of cursing Lucas. It is one of the daughters of the local ominous man named Tenorio. These accusations, of course, can’t result in any legal consequences, but the word of Ultima means a lot, especially because Lucas gets better almost immediately. This incident triggers the long-lasting hatred of Tenorio to Ultima.
Antonio finally goes to school. He starts studying, exploring science and religion at the lessons and continuing to learn from Ultima at home. He still has lots of fears and anxiety because of existential questions that haunt the boy, but it seems that Antonio finds the beginning of the way to reconcile all the controversial beliefs in his soul and mind. But another death shocks and alarms him: in the middle of the winter he sees Tenorio, rushing to their house. He claims that Ultima killed his daughter - the one she announced to be a witch - and now he goes for revenge. Narciso, who has a kind heart and is an old family friend despite his bad habit, tries to block Tenorio’s way, but the man shoots him down in cold blood. Narciso dies at once, but Tenorio reveals himself, so Ultima is safe for now. From the shock and being exposed to cold Antonio catches fever and lies daydreaming for several days, seeing vague prophetic images.
Soon he recovers and starts to prepare for his Communion. Not everyone shares his eagerness: his father Gabriel appears to worship the pagan Earth god much more than Christ. Another friend of Antonio named Florence is much more fond of science than of faith and often points to the illogical things in the Bible. But Antonio remembers Mary’s words and takes Communion as another mystical ritual that will reveal to him the mysteries of God, the purpose of the whole world and himself and the way to fight wrong things. On Easter Sunday Antonio finally goes through the Communion, but to his greatest disappointment he feels nothing different. No mysteries are revealed to him, he still doesn’t understand the nature of conflict between his father and brothers and is still as bitter about the evil in the world as he was before.
Antonio asks Ultima about that and she repeats her very first lessons about the importance of making your own choices and exploring the concept of goodness. Gradually she starts to take her apprentice to the more difficult tasks than gathering the healing herbs. Once they together go to an old house. Its owner claims that the house became haunted. When Ultima and Antonio come there and explore the house, the old woman discovers that Tenorio (or his second daughter) cursed the house to get rid of the family that lives in it. Ultima dispels the curse and drives off the ghosts - but soon after the only Tenorio’s daughter left alive falls ill, he starts to seek the way to kill Ultima with even more devotion.
Soon after that Florence accidentally drowns while swimming in the river. So many deaths and evil seen in a mere year finally break Antonio. Ultima insists on sending him far from home, to the farm of his uncles. Antonio gradually recovers there spending a carefree summer, perfectly average for a happy child of his age. Before leaving he discovers that Ultima can’t be killed in average way: her soul is bound to the life of her tamed owl. Now Antonio is relieved, he is sure that Tenorio won’t do any harm to Ultima. Another great news are heard from his father. Gabriel decides to reconcile with Mary’s family and finally stop arguing about Antonio’s fate. Now the boy will be free to decide on his own.
But when Antonio is ready to return home to resume his studies, Tenorio appears near his uncles’ farm. Enraged that he can’t kill Ultima he tries to attack the boy. Antonio has to run as fast as he can. He notices an owl flying around and looking after him. When Tenorio is ready to shoot the boy his uncle Pedro comes to the rescue, knocking off the villain. Unfortunately, Tenorio manages to shoot the owl.
Antonio understands that it was Ultima’s owl. He runs home to see Ultima dying. Unable to do anything he asks her to bless him and she does, giving her apprentice the final guidance before passing away. The story ends with Antonio, burying Ultima’s owl in a way she asked him with her last words.