Game of Thrones is finally returning to HBO next year with the prequel series House of the Dragon, but the network initially had different plans. A new book reveals the network threw away $30 million on another prequel pilot that will never see the light of day. HBO scrapped the untitled series based on the franchise which was set to star Naomi Watts.

According to the book, Tinderbox: HBO's Ruthless Pursuit of New Frontiers, the network decided to shelve the project altogether when the spinoff didn't deliver on the premise of the original series.

RELATED: Deleted Dollars: Four Expensive Cancelled Films

The spinoff was from Jane Goldman, who wrote the Kingsman film series, and was to take place thousands of years before the events of Game of Thrones. The doomed Thrones' prequel was reportedly filmed in Northern Ireland last year.

In the book WarnerMedia chairman Bob Greenblatt revealed how the network ended up making such a costly mistake:

“They had spent over $30 million on a Game of Thrones prequel pilot that was in production when I got there,” Greenblatt says in the book. “And when I saw a cut of it in a few months after I arrived, I said to Casey, ‘This just doesn’t work, and I don’t think it delivers on the promise of the original series.’ And he didn’t disagree, which actually was a relief. We, unfortunately, decided to pull the plug on it, there was enormous pressure to get it right and I don’t think that would have worked.”

On the same day news broke that the series was not moving forward, HBO confirmed that it was giving a full series order to House of the Dragon. The prequel is set much closer in time to Game of Thrones. The decision to order the spinoff directly to the series was to avoid another costly failed pilot.

“I'm the one who encouraged Casey to greenlight it to series,” said Greenblatt. “I said, 'Let's not risk $30 million on a pilot.' You can't spend $30 million on a pilot and then not pick it up. So, I said, 'Let's not make a pilot. Let's get a great series that we feel good about, and just make it. Or not’.”

House of the Dragon is set to air in 2022. HBO also has two animated spin-offs in production, according to reports.

READ NEXT: Chris Hemsworth's Mad Max Prequel Could Be "Biggest Film Ever Made" In Australia

Sources: HypeBeast