One of the criticisms levelled at the second season of House Of The Dragon was that it felt like it was building up to something massive, but then the season ended before things went truly crazy across every kingdom, family, and power bloc.
This was deliberate, as season 3 is not only the biggest season so far in terms of scope, it also covers four major events from the books that really kick things into high gear. The show will only run for four seasons, so this is a big escalation point for the story.
The last season ended with many threads being laid out.

The Rhaenyra-Alicent impasse proved immovable, as in a role reversal, Alicent visited Dragonstone, conceding that Rhaenyra must sit on the Iron Throne. She agreed to let Rhaenyra kill her son, King Aegon II, to end the war, but Rhaenyra told her it was too late for peace, as the conflict had already escalated beyond them.
Larys Strong smuggled the maimed Aegon II out of King’s Landing, planning to hide in Essos until Rhaenyra and Aemond destroy each other, allowing Aegon to return later.
After visions of the White Walkers, Daenerys Targaryen, and the future, Daemon saw himself as a piece in a larger, supernatural war. He abandoned his claim, pledging total loyalty to Rhaenyra as the rightful queen, having finally accepted the responsibility of the Song of Ice and Fire prophecy.
The season concluded with a montage of forces mobilizing, with Black’s dragonriders prepared, the Triarchy sailing to break the blockade, and the Starks moving south. Meanwhile, Rhaena Targaryen succeeded in finding and bonding with the wild dragon Sheepstealer.
Returning cast members include Emma D’Arcy as Rhaenyra, Olivia Cooke as Alicent, Rhys Ifans as Otto, Steve Toussaint as Corlys, Sonoya Mizuno as Mysaria, Fabien Frankel as Criston Cole, Harry Collett as Jace, Tom Glynn-Carney as Aegon II, Ewan Mitchell as Aemond, Bethany Antonia as Baela, Phoebe Campbell as Rhaena, Phia Saban as Helaena, Tom Taylor as Cregan Stark, Tom Bennett as Ulf White, and Freddie Fox as Ser Gwayne.
House of the Dragon returns for its third season on HBO in June.