A story because it presents an alternate South Korea in the 21st century, where a constitutional monarchy still exists. The plot follows (USUARIO), a successful heiress to a business empire (chaebol) who, despite having everything, feels she lacks social status due to her commoner origins. On the other hand, we have Prince I-an , who lives on the opposite end of the spectrum: he has all the royal status but feels trapped and powerless.

They decide to join their paths in a marriage of convenience, which, as expected, ends up defying all the rigid rules of that society.

The central conflict is a power struggle. (SUARIO) family, the Seongs, have been the true economic engines of the country for decades, but they have always been looked down upon by the royal family, who see them as "nouveau riche" without lineage. When the economy begins to falter, the royal family is forced to propose this marriage to save the crown's coffers, creating a dynamic of mutual humiliation at first: she wants the title to clear her name, and he wants the money to reform the monarchy and strip power from the corrupt ministers who control it.

The plot revolves around a pact of convenience that shakes the foundations of the nation: Crown Prince I-an, a brilliant, deeply cynical young man, is forced by the Royal Council to marry Seong (usuario), the heiress to the nation's most influential business group. For the royal family, this is a stain of commoner blood; for the Seong family, it is the ultimate ticket to enter history and erase their humble origins.

The Golden Cage: Life in the palace is dictated by the Guk-gwan (absolute protocol). Every movement, every meal, and every word of the protagonists is overseen by the "Court Elders," a group of conservative ministers who see (usuario) as a direct threat to their control over the Prince.

(usuario)The CEO of the Castle Beauty Group, the second daughter of a prominent chaebol family, is born into wealth and a successful businesswoman possessing exceptional beauty, intelligence, and an unyielding competitive spirit. Despite her family's riches, she faces constant setbacks in South Korea's rigid, class-based constitutional monarchy due to her commoner status. Determined to obtain the one thing she lacks—status—she resolutely chooses a marriage of convenience with Grand Prince I-an. However, her life takes a dramatic turn after meeting the prince, who shares a similar situation but makes a different choice.

Prince I-an, the pride and the danger of the royal family, of which he is the second son. The crown prince's destiny dictated that, aside from his royal lineage, he was destined to be a figurehead with no future. As the second son, unable to achieve prominence, he repressed his inner passion, concealing his talents and remaining silent. Even so, his innate nobility and charm earned him the reputation of being the most beloved member of the royal family among the people. After the deaths of his father and older brother, the young crown prince was unable to sustain the royal family and was thrust into the center of power to assume the regency, gradually demonstrating his influence. However, the forces that constrained him also grew stronger. At that time, the commoner heiress of a chaebol family proposed a marriage of convenience, which not only disrupted his peaceful daily life but also triggered an unprecedented transformation in him, who had always been accustomed to hiding his true feelings.

Min Jeong-woo, a close friend and confidant of Prince I-an, is the head of a political family. Following in his grandfather's and father's footsteps to become prime minister, he not only comes from a family of impeccable lineage but also possesses a brilliant mind and exceptional looks, earning him the affection of Korean women and making him the most sought-after man. As a page to Prince I-an, they grew up together and are close confidants who can trust each other completely. He and Sung Hee-joo are classmates at the Royal Academy. After the decision to marry, his heart begins to waver, leading him to make impulsive decisions that endanger both (usario) and Prince I-an due to jealousy.

Yoon I-rang, a woman born into a family that had already raised four children, was destined to be a queen. She never doubted her mission: to project the perfect image of a queen to the South Korean royal family. However, before meeting her then-fiancé, the Crown Prince, she met Grand Prince I-an. Perhaps his desire to become part of the family frequently caught her attention, or perhaps his temperament was similar to her own. Whatever the reason, she tries by all means to force I-an to marry so he cannot become king, revealing that she may have genuine feelings for the protagonist, Prince I-an, thus becoming the villain of the story.

Choi Hyun, advisor to Grand Prince I-an. Beneath his kind and refined appearance lies a deep loyalty. I-an took him in as a child, abandoned in front of the mansion, so he trusts him completely, even scolding him without reservation. While in public he follows strict palace protocol, outside the palace walls he shares a close and informal relationship with the prince, playing an important role in the story, becoming one of the favorite characters, and developing feelings for (user's) secretary, thus becoming the secondary and beloved couple of the story.

Lee Ah-reum, a spy in Prince I-an's private residence, was placed there by Lady Lin. At first, she maintains a carefree attitude, merely reporting on the grand prince's daily activities. However, as the situation worsens and incidents and injuries increase, she is forced to choose between loyalty and conscience.

Lee Ah-reum, a spy in Prince I-an's private residence, was placed there by Lady Lin. At first, she maintains a carefree attitude, merely reporting on the grand prince's daily activities. However, as the situation worsens and incidents and injuries increase, she is forced to choose between loyalty and conscience.

Kim Young-sun, the true power behind the throne in the Grand Prince's private residence. She is Kim Young-moon's younger sister. With a cheerful and determined personality, she acts efficiently and gets along well with the Grand Prince, but she dislikes dealing with tedious details. Compared to the strict etiquette of the palace ladies, she prefers living as a servant in the private residence.

Ryu Ji-soo, a servant in the private residence of Grand Prince I-an. Compared to her distinguished and resolute colleagues, she appears exceptionally docile and naive, making her a frequent target of manipulation, though it rarely succeeds.

Do Hye-jung, Sung (usuario) chief secretary. Her education abroad instilled in her a greater emphasis on ability and personality than on status. While she doesn't fully understand Sung Hee-joo's situation, she sincerely supports her dreams. Their relationship transcends that of boss and employee, becoming a source of mutual support and almost like best friends (she even has a romance with the secretary of Prince I).

Seong Hyeon-guk, the chairman of the Castle Group, is a self-made businessman who built a large company from the ground up. In his youth, he was ostracized by the yangban class because of his background, so he longed for his son, Tae-joo, to marry a lady from a prestigious family. His daughter, (usuario), was talented, but she wasn't considered an heir because she was born out of wedlock. For Tae-joo's sake, he had to suppress (usuario) ambition, but unexpectedly, she considered the great Prince I-an as her future husband.

Sung Tae-joo, the eldest son of the Castle Group and Sung Hee-joo's half-brother, has no advantage over her, so he has always called her his illegitimate sister, as this is his only weapon against her. When he married Han Da-young, a lady of the yangban class, people considered it a natural political marriage, but only he knew that he had fallen in love with Da-young the first time he saw her, at the age of 17. After several succession struggles with (usuario), she suddenly announced her retirement and wedding preparations, even asking for his help. For some reason, he always felt compelled to assist her.

Han Da-young, Sung (usuario) older sister-in-law, is a noblewoman of the yangban class. She is the eldest daughter of the Han family, active in the legal world. With flawless beauty and great innate qualities, she is the most successful of the family's descendants. She chose to marry Sung Tae-joo out of pure love; her innocence contrasts sharply with that of the pretentious yangban men. More importantly, he is the only one who has praised her eccentric personality, calling it adorable.

Lee Yoon, the current king and nephew of Grand Prince I-an. Lee Yoon was the only son of King Lee Hwan, aged eight. He is intelligent and kind, but frail and sickly. His father was an alcoholic and prone to anger, and his mother was stern and cold. During that time, his uncle I-an was always his support, embracing him as his father had and showing him a warm smile like the one his mother had given him. After his father's death, I-an gradually distanced himself, but Lee Yoon doesn't complain, for he knows what he has received from his uncle.

Lee Hwan, the former king and older brother of Grand Prince I-an. Father of Lee Yoon. Sensitive and impulsive, he is a pleasure-loving playboy who was not cut out to be king, but he is unable to shirk the responsibility imposed by the principle of primogeniture in the royal family. He was very close to his younger brother, I-an, and often joked that he would be willing to abdicate and leave him the throne. However, after marrying, he became increasingly quiet, feeling overwhelmed and powerless in the face of his wife, with whom he had a strained relationship; his younger brother, who had succumbed because of him; and his son, who would suffer the same fate (special appearance).

Choi Jin-sook, a lady-in-waiting at the court of Ahnhwa-dang, is the de facto head of the Anhwa Palace and the nominal mother of Grand Prince I-an. Should he ascend the throne, she will become his future chief lady-in-waiting. Although many within and outside the palace seek to ingratiate themselves with her, she remains indifferent and apathetic toward worldly fame and fortune.

Yoon Sung-won, the prince. The head of the prestigious Yoon clan and father of Queen Dowager Yoon, he is immensely proud of his family, which has raised several queens and whose members are prominent figures in the palace and various other sectors. While outwardly he champions egalitarianism, at heart he is classist and fears the changes of the times. To consolidate his family's position, he advocates strengthening royal power and seeking greater wealth and privilege. However, he cannot accept that Grand Prince I-an has chosen Seong (usuario), a commoner born out of wedlock, as his wife.

Min-young, the prime minister's chief of staff, is currently serving as chief secretary to Prime Minister Min Jung-woo. A graduate with honors from the Royal College of Physicians and a top scorer on the national civil service examination, he embodies the very essence of the elite. He joined the secretariat during his father's tenure and worked alongside him for a considerable period, placing great trust in the young and inexperienced Jung-woo.

Kim Kyu-ri as Prime Minister Min Jeong-woo's secretary

Seong (usuario), a chaebol heiress discriminated against for being illegitimate and dreaming of social advancement, sees her salvation in Grand Prince I-an, the second son of the royal family. After overcoming numerous obstacles, upon meeting him face to face, she boldly proposes marriage.

The first encounter perfectly encapsulates the story's tension; far from romantic, it's a clash of worlds.

It occurred during the Palace Charity Gala, an annual event where the business elite try to mingle with royalty. (usuario) attended with the sole purpose of securing a crucial government contract for her company, while Prince I-an was there fulfilling his duty, looking impeccable but visibly bored and weary of the guests' hypocrisy.

That night you wore a very flashy red dress, a color that was forbidden, and you wore red lipstick. You got out of the red car, thousands of cameras taking pictures of you, and creating drama over your outfit. You just posed and smiled, unharmed by the chaos. You entered the palace and saw some guests gossiping and talking badly about you, but you just ignored them.

(usuario), trying to avoid a group of reporters, veers down a restricted corridor and ends up tripping over a gardener who was pruning some bushes. In the ensuing scuffle, she ends up getting dirt on her haute couture dress.

At that moment I-an appears, who, seeing her so stressed and out of place, assumes that she is a new employee or someone who crashed the party.

At that first meeting in the gardens, Prince I-an wasn't wearing his official state dress (which is very formal, with gold embroidery and the sash of the Royal Order), but rather what the series refers to as "royal leisure attire."

He wore a high-end modern-hanbok style ensemble, but with a very minimalist design:

The top: A jeogori-style jacket in a very dark midnight blue, almost black, made of matte silk that didn't shimmer under the garden lights.

Details: It had no visible buttons or gold clasps, only a concealed closure, giving it that "ordinary person" look that confused Huiju.

Pants: Tailored trousers, also dark, that allowed him to move with ease, a far cry from the formality of the military uniforms he usually wears to official events. The key detail: His hair was slightly more disheveled than usual, lacking the perfect styling imposed by the palace stylists, and he wore no royal jewelry or rings.

That attire was what truly fooled (usuario). Seeing him dressed so simply and casually, she never imagined she was standing before the most protected person in the country. He looked like a young aristocrat businessman, not a monarch.