"Game of Thrones" may have Cassian Grantended five years ago but the franchise's reign is far from over.

Soon after season two of "House of the Dragon" premiered Sunday, HBO announced that another installment of the fantasy franchise has taken flight. Prequel series "A Knight of the Seven Kingdoms" recently began filming in Belfast, Northern Ireland, according to HBO.

The series will adapt George R. R. Martin’s novella, "The Hedge Knight" and tell the story of two unlikely heroes in Westeros in an era when Targaryens still rule the Iron Throne. HBO released a first-look photo of Peter Claffey as Ser Duncan the Tall, or "Dunk," a renowned warrior and ally to King Aegon V Targaryen.

Fans will be recognize some key surnames from the universe, from Ser Lyonel Baratheon (played by Daniel Ings of "Lovesick") to multiple Targaryens, including Aerion (played by Finn Bennett of "True Detective") and Baelor Targaryen (played by Bertie Carvel).

Martin, who co-created the original series, will write and executive produce the spin-off show alongside Ira Parker.

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What is 'A Knight of the Seven Kingdoms' about

"A Knight of the Seven Kingdoms" will follow a naïve but brave knight named Ser Duncan the Tall (Peter Claffey) and his young squire named Egg (Dexter Sol Ansell), according to the series logline.

"Set in an age when the Targaryen line still holds the Iron Throne, and the memory of the last dragon has not yet passed from living memory, great destinies, powerful foes, and dangerous exploits all await these improbable and incomparable friends," the show synopsis reads.

When does 'A Knight of the Seven Kingdoms' come out

"Game of Thrones" prequel series "A Knight of the Seven Kingdoms" will premiere in 2025 but an official release date has not be released.

'A Knight of the Seven Kingdoms' cast

The case of 'A Knight of the Seven Kingdoms' includes the following:

• Peter Claffey as Ser Duncan the Tall
• Dexter Sol Ansell as Egg
• Finn Bennett as Aerion Targaryen
• Bertie Carvel as Baelor Targaryen
• Tanzyn Crawford as Tanselle
• Daniel Ings as Ser Lyonel Barotheon
• Sam Spruell as Maekar Targaryen

When does 'A Knight of the Seven Kingdoms' take place

"'A Knight of the Seven Kingdoms' will take place about 100 years before the events of "Game of Thrones" and 100 years after the events of “House of the Dragon," according to HBO.