HBO spent a whopping $30 million on the pilot for cancelled Game of Thrones prequel The Long Night, a new book reveals. Next year, the Targaryen-led House of the Dragon will be the first spin-off to emerge from the aftermath of Game of Thrones' 2019 conclusion, but it almost wasn't. Eager to extend the monumental success of Game of Thrones, HBO has been developing countless potential spin-offs since even before the flagship series drew to a close. Back in 2018, it seemed likely that the first show to arrive would be one tentatively named The Long Night.

This series, which was overseen by Jane Goldman and Game of Thrones author George R.R. Martin, was expected to be set about 10,000 years before the events of the original show. It would've covered the events of the first Long Night, or the period of time when the White Walkers invaded Westeros. Naomi Watts was hired to lead the series, which also included stars like Josh Whitehouse, Jamie Campbell Bower, Georgie Henley, and Naomie Ackie. The Long Night made it as far as the pilot before HBO pulled the plug in the fall of 2019.

Related: One House Of The Dragon Change Hints Why Game Of Thrones Failed

Now a few more details about HBO's decision regarding The Long Night has been revealed thanks to James Andrew Miller's new book Tinderbox: HBO's Ruthless Pursuit of New Frontiers (via Insider). Former WarnerMedia chairman Bob Greenblatt joined the company when the pilot was already in the works. Upon seeing a cut of the episode, Greenblatt turned to HBO's chief content officer Casey Bloys and shared his honest thoughts. Greenblatt said in the book:

"They had spent over $30 million on a 'Game of Thrones' prequel pilot that was in production when I got there. 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."

The Night King raises his arms at Hardhome in Game of Thrones

Greenblatt then concluded, "There was enormous pressure to get it right and I don't think that would have worked." Few details have been revealed about the Game of Thrones prequel, with Watts at one point saying she was hesitant to reveal anything about her experience on the pilot in case any aspects of it are someday absorbed into another project. However, it sounds like The Long Night didn't have anything that could justify its massive budget. Perhaps this means the production values were found lacking, or that the story wasn't strong enough to propel the rest of the series forward.

Game of Thrones had a famously terrible first pilot as well, so the fact that The Long Night's was enough to shelve the entire series likely speaks to how the production went. It might've actually been better than Game of Thrones', but the eventual quality of the flagship series meant it still wasn't good enough. Now, House of the Dragon carries HBO's high expectations, and only time will tell if it can reach the impressiveness of Game of ThronesIt at least got a series order, which is more than The Long Night can say.

More: House Of The Dragon Risks Repeating Game Of Thrones Season 8 Blunder

Source: Tinderbox: HBO's Ruthless Pursuit of New Frontiers (via Insider)