Dang Duang Haruethai (Princess Of My Heart)

Rangsiman, the King of Kasik, receives news that Princess Manisara of Tanta—his betrothed—has disappeared near the border of the three kingdoms: Kasik, Panthurat, and Tanta. Believing she has crossed into Panthurat, he decides to investigate personally. In reality, Princess Manisara fled intentionally to avoid marrying King Rangsiman, who is notorious for his ruthlessness.
While escaping through the Panthurat border, the princess's horse gets caught in a hunting trap. She is rescued by Prince Thayutithorn, the Crown Prince of Panthurat, who takes her to the Pompuen Pavilion to recover. Princess Thassika, the younger sister of Prince Thayutithorn, learns of this and prepares to bring Manisara to the inner court. However, along the way, Princess Thassika is abducted by King Rangsiman to be held as a hostage. This forced proximity allows the two to learn about one another's true nature.
Meanwhile, Sathin, the Minister of Interior for Kasik, grows anxious when he cannot contact the King. His daughter, Meena, grew up with the King and his loyal officers, Benlee and Rachid. Although the King cares for Meena like a sister, she is secretly in love with him. Upon tracking him down, Meena discovers he is holding Princess Thassika captive.
Back in Panthurat, the Queen Mother returns from her summer palace to find Thassika missing. She orders Manisara to stay in the inner court and notices a growing spark between Thayutithorn and Manisara. In Kasik, Rangsiman brings Thassika to the Isinthorn Pavilion and has her accompany him on his royal duties. The King instructs Rachid to tell Sathin to send a proposal to Panthurat: Panthurat must take responsibility for the slight against Princess Manisara’s honor, while Kasik will take responsibility for Princess Thassika.
However, the ambitious Sathin refuses to deliver the message and secretly poisons the Chief Minister. Meena is shocked by her father’s treasonous plot but, upon realizing the King truly loves Thassika, her heartbreak leads her to join her father's coup.
Thassika overhears the proposal sent by the King and, feeling slighted, tries to escape with Rachid’s help but is caught. King Rangsiman finally confesses his love for her, and they reach an understanding. He agrees to send her back to Panthurat and gifts her the Crown of Kasik. On the journey back, Sathin’s assassins ambush them, leaving the King critically wounded. Thassika rushes him to the Pompuen Pavilion for surgery.
The Queen Mother orders Manisara to care for the King as his fiancée. Ultimately, King Rangsiman forces an audience with the Queen Mother to declare his feelings for Thassika and ask for her hand in marriage. Rachid brings Meena to Panthurat, and Rangsiman believes she has repented. However, Meena kidnaps Thassika. Rangsiman immediately leads his forces back to Kasik, only to fall into Sathin’s trap. He must now risk everything to save Thassika, the woman who is the "Gleam of His Heart" (Dang Duang Haruethai).