A group of children residing in an orphanage share rumors about the infamous siblings, Julien and Marguerite de Ravalet, who are fugitives accused of incest. One of the caretakers recounts their tragic story.
As youngsters, Julien and Marguerite shared a profound bond, demonstrating an unwavering devotion to one another. After an incident where Julien saves Marguerite from a fall while riding, their uncle, Abbot, grows concerned about the intensity of their relationship. He urges their father, Jean, to send Julien and his older brother Phillipe abroad to study, claiming that Marguerite is hindering their academic progress.
Years pass, and Marguerite, adamant against marriage, spends her time in solitude. When Julien and Phillipe return home, a heartfelt reunion ensues between Julien and Marguerite. Their parents, however, have arranged for Marguerite to marry Marigny, a kind but disabled man. Uninterested in this match, Marguerite finds herself increasingly jealous of Marigny, while Julien grapples with his own feelings of jealousy over the engagement.
During a dinner with Marigny, Julien excuses himself, and Marguerite follows him, leading to an intense moment when they find themselves alone. The attraction between them is palpable, but they resist acknowledging their feelings. Instead, they engage in a flirtatious game, testing each other's resolve as they explore their desires.
When their parents catch them partially undressed, they face severe consequences for causing Marigny to withdraw from the engagement. In a secret meeting, Marguerite confesses her love for Julien, but despite his mutual feelings, he turns her down. Heartbroken, Marguerite is later married off to Lefevbre, a wealthy tax collector. However, the marriage quickly becomes a nightmare, as he tries to consummate their union against her will, leading Marguerite to reject him and seek refuge in solitude.
As Lefevbre grows increasingly abusive, Julien learns of her plight and intervenes, beating Lefevbre and allowing Marguerite to escape. That same night marks a pivotal moment as Julien and Marguerite consummate their love for the first time.
A maid discovers the couple in bed, leading to the family's outrage. As tensions rise, their father considers sending Julien away, but their mother, prioritizing her children’s happiness, facilitates their escape. Unfortunately, Lefevbre accuses them of incest and adultery, branding them as fugitives.
After weeks of evading capture, Marguerite learns she is pregnant. Disguised as a man to protect her identity, their evasion comes to an end when authorities receive a tip-off about their location. Just as they attempt to flee to England, they are apprehended.
During the trial, both siblings deny the allegations, claiming they fled due to Julien's efforts to rescue Marguerite from her abusive husband. Their father petitions King Henri IV for clemency, but the king is unforgiving, declaring he cannot condone incest. Amid the courtroom turmoil, Marguerite gives birth to a son, who is subsequently placed in the care of a nunnery.
As the trial concludes, both Julien and Marguerite are found guilty and sentenced to death. In a desperate plea, Marguerite begs for her brother's release, proclaiming her sole guilt, but her cries remain unanswered.
The following day, as they stand at Place de Grève awaiting execution, Julien faces the guillotine first. In a tragic turn of fate, Marguerite succumbs to the shock of witnessing her brother's death before she too meets the same fate. In the aftermath, the Château is left desolate.
In a poignant conclusion, Julien and Marguerite's father and brother orchestrate a plan to rescue the baby from the nunnery. The nun entrusted with this task reveals that Marguerite had named her child Julien before her tragic demise. The de Ravalet family departs, taking the infant with them, symbolizing the enduring legacy of their love amidst heart-wrenching circumstances.
