A massive twist is coming to Game of Thrones ... but only in the book series.

Author George R.R. Martin recently told IGN that he's working on a twist for his upcoming book The Winds of Winter, but it's something that will not occur in the television show. The reason is simple: It concerns a character that died in the show but not in the novels.

"It is something that involves a couple of characters, one of whom is dead on the show, but not dead in the books," Martin said. "So the show can’t do it, because they have killed a character I have not killed."

Characters still alive in the novels but dead on the show include Barristan Selmy, Jojen Reed, Princess Myrcella, Shireen, Mance Rayder, Queen Selyse and Stannis Baratheon. There are a whole lot of others, but it's probably safe to say Martin isn't about to pull out a random twist involving Daenerys' horserider Rakharo.

Martin originally discussed this latest plot turn in an interview with Entertainment Weekly last year, although at that time he was unsure whether he'd actually go through with the plan.

"It’s easy to do things that are shocking or unexpected, but they have to grow out of characters," Martin said at the time. "They have to grow out of situations. Otherwise, it’s just being shocking for being shocking. But this is something that seems very organic and natural, and I could see how it would happen."

You probably shouldn't get too hyped for The Winds of Winter just yet, though, because we still have absolutely no idea when or if it will ever hit store shelves. Last year, Martin had a deadline of October 31st but failed to meet that date, as we previously reported. With the new season, Game of Thrones will for the first time be venturing into material not yet covered in A Song of Ice and Fire.

Game of Thrones returns for its sixth season on April 24.