Ignacio, portrayed by Jack Black, is the son of a Scandinavian Lutheran missionary and a Mexican deacon, whose attempts at converting each other led to an unexpected marriage. Tragically, they both pass away while Ignacio is still a child, leaving him to grow up in a monastery where he works as a cook. Despite his dedication to caring for the orphans, his culinary skills leave much to be desired, largely due to the poor quality of ingredients he is able to procure.
One fateful night, Ignacio finds himself robbed of the orphans' tortilla chips in a dark alley. This incident ignites a fire within him; he yearns to not only secure better food for the children but also to earn the respect of the other friars. He grapples with his feelings for Sister Encarnacion, the new tutor who captures his heart, and contemplates defying the monastery’s strict rules against wrestling.
Determined to fulfill his dreams, Ignacio adopts the name "Nacho" and teams up with the thief, Steven, who takes on the moniker "Esqueleto" (Skeleton). Together, they brave the local Lucha Libre competition, although they initially face defeat in their first match. Undeterred, Ignacio learns that every wrestler receives a share of the revenue despite their performance, which inspires him to continue. With the earnings from their weekly matches, Ignacio is finally able to improve the quality of the food he serves the orphans, who are oblivious to his secret life until one inquisitive child named Chancho discovers the truth but vows to keep it hidden.
As Ignacio faces ongoing losses in the ring, he seeks guidance from a mystical figure known as "Emperor," who instructs him to climb an eagle's nest, crack open an egg, and consume the yolk to gain strength. Yet, even after following this bizarre advice, he suffers another defeat. In search of a true mentor, Ignacio approaches Ramses, a celebrated Luchador, only to discover that the idol he admired does not meet his expectations when Ramses treats him poorly.
The turning point comes when Ignacio's wrestling secret is exposed in a rather dramatic fashion when his robe ignites during a prayer. He bravely reveals his identity as Nacho and announces his aspiration to compete at the "Battle-Jam," a fierce tournament that will grant the winner a showdown with Ramses and a chance to earn a cash prize for the orphans. With newfound determination, Ignacio and Esqueleto engage in a series of matches against other notable wrestlers, vying for the opportunity to challenge Ramses.
Ultimately, the quiet yet formidable wrestler Silencio claims victory, forcing Ignacio to step back into the shadows for a time. However, hope reignites when Steven brings news—Silencio can’t fight due to an injury caused by Steven himself, and Ignacio is compelled to take his place in the ring. Distrustful yet hopeful, Ignacio reaffirms his partnership with Steven and sends a heartfelt message to Encarnacion through him, professing his feelings for her.
During the championship fight, Ignacio initially struggles but with the fervent support of the crowd and the presence of the orphans, he finds the strength to overcome Ramses’ underhanded tactics. Despite facing disqualification when his mask is torn away—an act of dishonor among Luchadores—Nacho channels his earlier experiences and bursts forth, ultimately defeating Ramses.
In victory, Ignacio doesn’t just claim the title but also the prize money, which he dedicates to purchasing a bus for the orphans’ educational trips. The film concludes with an exploration of camaraderie and growth as Ignacio, Steven, and Sister Encarnacion take the children on an adventure to the ancient Zapotec city of Monte Alban, symbolizing a new chapter in their lives where Ignacio has not only gained respect but may have also won the heart of Sister Encarnacion.
