House of the Dragon Episode 1 has been titled as "The Heirs of the Dragon".
The sick & weak King Jaehaerys in hopes to end the civil war names his oldest grandson Prince Viserys as the heir to the iron throne over Princess Rhaenys.
In King's Landing, King Viserys is soon going to be a father & an heir's tournament is organized as a way of celebration.
In unfortunate turns of events Queen Aemma goes in labor & the child get's breached leading to death of Queen as well as their new born son Baelon.
Prince Daemon, the Lord Commander of the City Watch indulges in mass violence & mocks his bother's death by naming him "The Heir for a Day".
King Viserys after getting frustrated & on the advice of Hand of the King, Ser Otto Hightower strips Daemon of all his title & send him to Vale.
Thus, Princess Rhaenyra Targaryen is named the heir to the Iron Throne by Viserys & a horrendous prophecy is revealed.
And, Prince Daemon with his mistress leaves King's Landing on his dragon named Caraxes.