Hedy is a nineteen-year-old Jewish-Austrian actress of immense beauty and intellect. Although she enjoys the thrill of performance, her notoriety from a controversial film role makes her vulnerable to public scrutiny. Beneath her glamorous exterior, she possesses a sharp, analytical mind nurtured by her father. She relies on her ability to observe others and adapt her personality to survive the restrictive societal expectations placed on women in 1930s Europe.

Fritz is a wealthy Austrian arms dealer known internationally as the "Merchant of Death." He holds immense political sway over Austria's leaders and maintains business connections with fascist dictators. He hides his half-Jewish heritage while aligning himself with anti-Semitic powers to secure his financial interests. Obsessed with control, he views a beautiful wife as an accessory to his power and actively suppresses any independence.

Hedy's father is a reliable, well-dressed bank manager who deeply loves his daughter. Unlike the rest of their conservative Austrian society, he takes her ideas seriously and regularly discusses politics, art, and science with her. He is keenly aware of the delicate political situation in Europe and fears for his family's safety due to their Jewish heritage.

Mrs. Kiesler is a former concert pianist who abandoned her musical career to become a traditional Austrian housewife. She strictly enforces the era's gender expectations and frequently criticizes Hedy's modern, independent choices. Her stern demeanor masks a practical desire to keep her daughter safe by ensuring she conforms to acceptable social standards.

George is an American composer who bonds with Hedy over their shared intellect and musical understanding. Unlike many men in the studio system, he recognizes her sharp mind and treats her as an equal. He becomes her partner in an ambitious project to develop a new radio frequency system to aid the Allied forces.

Mayer is the powerful head of MGM Studios who scouts European talent. As a Jewish immigrant himself, he is cautious about introducing European Jews to American audiences. He focuses heavily on marketability, offering actresses a path to stardom in exchange for controlling their public image, history, and behavior.

Ilona is Hedy's Hungarian roommate in California. She helps Hedy survive the dangers of the Hollywood studio system, offering camaraderie and physical protection from predatory executives. The two also bond over their shared anxiety regarding the political situation in their home countries.

Gene is an American screenwriter who offers Hedy a sense of normalcy and safety in California. He thrives in the Hollywood social scene and prioritizes networking at parties over quiet evenings at home.

An Austrian prince and close associate of Fritz Mandl. He represents the elite Austrian political class who attempts to maintain power amid the rising threats from neighboring fascist dictatorships.

The younger brother of Prince Ernst. He is known among the elite for his lack of foresight, a trait that makes him susceptible to manipulation in a high-stakes political environment.

The Italian dictator whose military alliance is crucial to Austria's continued independence. His presence at Fritz's home brings the terrifying reality of European fascism directly into Hedy's domestic life.

The wife of Louis B. Mayer. She is well aware of her husband's predatory behavior toward young actresses and actively uses her position to interrupt him and protect vulnerable women at industry events.

George Antheil's wife, who grows suspicious of her husband's lengthy absences from home. She initially struggles to believe that a glamorous actress could be involved in complex scientific work.

A young child adopted into the Markey household. He represents a tangible way for Hedy to rescue vulnerable children from the European crisis and provides her with a profound sense of purpose.

A maid who shares a striking physical resemblance to Hedy. She is intentionally hired for this similarity and plays an unwitting role in the household's internal dynamics.

The leader of the Nazi Party. His invitation into Fritz's home confirms the darkest fears of the Austrian Jewish population and marks a turning point in the region's stability.

An officer on the military council reviewing naval inventions. He politely listens to technical presentations but maintains strict gender prejudices regarding who should be contributing to military science.