The long-awaited "Game of Thrones" prequel series, "House of the Dragon," has a new trailer.

The show, based on George R. R. Martin's 2018 book "Fire & Blood," takes place hundreds of years before the events of "Game of Thrones" and is a deep dive into the history of House Targaryen, the ancestors of Daenerys Targaryen (Emilia Clarke).

"House of the Dragon" centers on a brutal familial civil war that erupted over control of the legendary Iron Throne.

The trailer begins with the families pledging their loyalty to Paddy Considine's King Viserys Targaryen, and to his heir, Emma D'Arcy's Princess Rhaenyra Targaryen.

But all is not what it seems. "Men would sooner put the realm to the torch than to see a woman ascend the Iron Throne," Eve Best's Rhaenys Targaryen warns.

To that end, we see battle formations and hand-to-hand combat, even between female members of the families.

Steve Toussaint's Lord Corlys Velaryon voices over, "History does not remember blood. It remembers names."

The sneak peek ends with Matt Smith's Prince Daemon Targaryen coming face to face with a fire-breathing dragon.

"House of the Dragon" debuts Aug. 21 on HBO and HBO Max.