HBO’s A Knight of the Seven Kingdoms is about Dunk & Egg: the former, Ser Duncan the Tall, is a Hedge Knight who’ll one day become the Kingsguard’s Lord Commander; the latter is his squire, Aegon Targaryen, who will later become the fifth king to carry that name. The show will take place around 90 years before Game of Thrones’ timeline of events, meaning it will be quite a different Westeros, but that also allows it to add to the franchise’s rich history and mythology.
There won’t be too many direct Game of Thrones connections (nor to House of the Dragon, for that matter). The only really likely crossover character is a younger form of Maester Aemon Targaryen, who is Egg’s brother, but beyond him it can still deepen understanding of Westeros’ past and how that informs its present. That will not only include the Game of Thrones spinoff fleshing out the Targaryen dynasty and exploring new areas, but in solving a key mystery relating to Dunk and Egg’s deaths and Targaryen dragons.
A Knight Of The Seven Kingdoms Will Likely Explain The Tragedy At Summerhall
One of the biggest and oldest unsolved mysteries is what caused the Tragedy at Summerhall, a devastating fire at the Targaryens' residence in the Dornish Marshes that resulted in multiple deaths - including those of Dunk and Egg - with the shadow of Summerhall lingering over the Targaryens afterwards. Exactly what happened is unknown, but it is linked to Egg’s (by that point fully established as King Aegon V) desire to bring dragons back to the world. Writings from a Maester who died in the fire remain, though the ink is blotted meaning it gives only brief clues:
the blood of the dragon gathered in one …… seven eggs, to honor the seven gods, though the king's own septon had warned …… pyromancers …… wild fire …… flames grew out of control … towering … burned so hot that …… died, but for the valor of the Lord Comman …
It seems clear then there was dark magic afoot, with wildfire and pyromancers mentioned alongside the dragon eggs. While Martin himself has yet to confirm specifics, it’s a reasonable assumption that A Knight of the Seven Kingdoms: The Hedge Knight will show the event. It would mean the show covering a lot of ground - it takes place some 40 years after the story begins - but Martin himself wrote on his Not A Blog site that he wants to cover their story from "start to finish." It’s not unusual for shows to cover so much ground - House of the Dragon’s timeline spans multiple decades - and it’d be a major scene to put on TV.
The Tragedy At Summerhall Would Be A Knight Of The Seven Kingdoms' Perfect Ending
Assuming that A Knight of the Seven Kingdoms runs long enough (and has enough time jumps) to get there, then showing the Tragedy at Summerhall could well be its perfect ending - not least because, well, it is the ending. The Tales of Dunk & Egg is above all else the journey of those two characters and their friendship, and it ends with them dying together. Given it will show the beginning of their relationship, then it only seems fitting audiences get to see what becomes of these characters and they’re given a definite conclusion.
While A Knight of the Seven Kingdoms will (judging by the books) be much lighter in tone and far smaller in scale than Game of Thrones, the Tragedy at Summerhall would be an epic event worthy of a series finale. For those in the know, it could loom over the entire show. Meanwhile, the mystery, drama, death, and destruction surrounding the event would be great for an expanded on-screen story, and the conflagration itself should look great with the kind of large budget this show could have.
It would not only give the series a shocking, sad, and certainly memorable ending, but also connect to Game of Thrones too: none other than Rhaegar Targaryen is born during the Tragedy at Summerhall (and later in life is said to be haunted by the "shadow of Summerhall,") which feels like the kind of bittersweet nod - hope for the future amidst the death - that could make it a really great conclusion. With all of those elements combined, the A Knight of the Seven Kingdoms solving the Game of Thrones mystery makes a lot of sense.