HBO Reportedly Spent 'Over $30 Million On A Failed 'Game of Thrones Prequel Pilot

While the network gave the green light to “House of the Dragon,” it previously scrapped an untitled spinoff starring Naomi Watts.

And it cost them a lot of money, according to a new book titled Tinderbox: HBO's Ruthless Pursuit of New Frontiers by James Andrew Miller.

The book notes that the network shelled out more than $30 million on the pilot episode of the prequel series before pulling the plug.

Per Entertainment Weekly, the spinoff was set thousands of years before the hit series and focused on the distant ancestors of noble families like the Starks and Lannisters.

The outlet noted that since it predated House Targaryen's arrival in Westeros, it would not include dragons.

"They had spent over $30 million on a Game of Thrones prequel pilot when I got there," former WarnerMedia chairman Bob Greenblatt reveals in the book.

"And when I saw a cut of it in a few months after I arrived, I said to [HBO chief content officer] Casey [Bloys], 'this just doesn't work and I don't think it delivers on the premise of the original series.' And he didn't disagree, which actually was a relief. So we, unfortunately, decided to pull the plug on it. There was enormous pressure to get it right and I don't think it would have worked.”

Shortly after, the network announced that it would be moving forward with another prequel titled “House of the Dragon” instead. The 10-episode first season takes place 300 years before the events of GOT and focuses on the reign of House Targaryen.

The series, based on George R.R. Martin’s book “Fire & Blood,” got a straight-to-series order. “The Crown’s” Matt Smith, “Bates Motel” star Olivia Cooke, and Emma D’Arcy from “Truth Seekers” have all been cast in the prequel.

It is set to air in 2022.