In the year 1401, the renowned knight Tirant lo Blanc arrives at the port of Constantinople with his small but battle-hardened troupe of Almogavars. The city is in turmoil, as the emperor's only son has recently perished at the hands of the Turks, leaving the Byzantine emperor too frail to command the army effectively. With the ominous threat of an Ottoman invasion looming over the city, Constantinople desperately requires a capable military commander. Upon Tirant's arrival, he is welcomed by the emperor, who appoints him as the commander in chief of the Imperial army.
As Tirant meets the Empress and is officially introduced to the imperial family, he inadvertently catches a glimpse of the bold and beautiful Carmesina, the emperor's only remaining child, who is also known to be prone to nosebleeds. Just stepping into her adolescence and overflowing with youthful allure, Carmesina soon finds herself infatuated with the valiant and striking Tirant. She confides her burgeoning feelings for him to her guardian, Ines, nicknamed the Placid Widow, the widow of an ally to the anti-pope. However, the Placid Widow quickly dashes Carmesina's romantic aspirations, reminding her that despite Tirant’s bravery and skill as a military leader, he lacks the noble lineage and wealth commendable for courting the heiress of the Byzantine Empire.
Nevertheless, Carmesina's friends and confidantes, notably Pleasure-of-My-Life and Estefania, harbor different opinions. Concerned about an impending Ottoman incursion, Pleasure-of-My-Life, the daughter of the court's poet, encourages Carmesina to pursue her infatuation, hinting that married to Tirant, the future queen could protect her inheritance. Estefania, another lady-in-waiting who has developed feelings for Tirant's loyal right-hand man, Diafebus, also supports the budding romance as she wants her friend to be happy.
As the situation escalates, the empress contemplates the dire state of Constantinople against the looming Ottoman siege and believes marrying her daughter to Sultan Mehmed represents the only chance of survival for their empire. In the midst of this turmoil, Tirant successfully leads his troops against the forces of Sultan Mehmed II, emerging victorious but returning to court wounded, bearing the weight of the Ottoman threat still present.
The dynamics shift as Pleasure-of-My-Life rekindles Carmesina's desire for Tirant through vivid dreams laced with desire, while Ines, longing for Tirant herself, faces rejection as he brushes off her advances. Amidst this love-square, Estefania and Pleasure-of-My-Life orchestrate secret encounters for Tirant and Carmesina, allowing him to slip into her chamber. Yet, when Carmesina awakens and realizes Tirant's presence, panic ensues, and he narrowly escapes through a tower window, although not without injury — the glass gives way, and he breaks his legs in the process.
As Tirant tries to conceal the events of the night under the guise of a horse riding mishap, he ultimately ends up bedridden. During this time, the Empress engages in a secret affair with Hippolytus, a young member of Tirant's entourage, raising the stakes even further as the court teeters on scandal.
The plot thickens when an Ottoman emissary arrives seeking to propose marriage between Carmesina and Mehmed. The emperor asks for time before providing an answer, but Carmesina chooses to take control of her destiny. In a bold act, she visits Tirant in his tent, affirming her love for him intimately, despite the impending marriage. When she refuses to marry Mehmed for Tirant's sake, war inevitably erupts.
In a climactic battle, Tirant faces down the Sultan and kills him but suffers grievous injuries in the process. As he endeavors to return to Constantinople, he succumbs to his wounds, and devastated by the loss, Carmesina ultimately falls into despair and passes away from grief. Following the demise of the Byzantine Emperor, Hippolytus marries the Empress and claims the throne, while Diafebus and Estefania leave Constantinople, marking the end of an era defined by love, ambition, and tragedy.
