New details about "The Winds of Winter," the long-overdue latest installment from book series "A Song of Ice and Fire," are starting to appear online.

The sixth book from the series will feature the fictional language Dothraki, according language expert David J. Peterson, who has been involved with the books' TV adaptation "Game of Thrones" in the past.

The linguist revealed the information on Reddit, saying that he helped author George R.R. Martin translate some of the text of the upcoming book to the language spoken by the Dothraki tribe. The language is widely used by the series' nomadic horsemen to communicate. Peterson jokingly said that Martin will be mad at him for unveiling a major secret.

"I think he's annoyed with me for even saying that I translated stuff for him. I wouldn't be totally surprised if he doesn't use it and makes up something totally incongruous to punish me," the language expert said.

Meanwhile, Martin teased that he included a "major plot twist" in "The Winds of Winter." The author said that HBO might not be able to pull it off in their TV adaptation because they already killed the character involved in the explosive storyline.

"It is fairly obvious because it is something that involves a couple of characters, one of which is dead on the show, and not dead in the books," the author told IGN. "So the show can't do it, unfortunately, because they have killed someone I have not killed."

There are speculations going around about the dead character who will be involved in the major twist. Some are saying that it could possibly be Jon Snow (Kit Harington) or another deceased character in the TV series. However, the author chose not to divulge any more information about it.

At the moment, there is no word yet regarding the official release date of "The Winds of Winter."