This post contains discussion of Game of Thrones Season 5, Episode 3, “High Sparrow,” and a significant book plot that could conceivably still make it into the show. If you’re worried about reading up on either of those things, now would be the time to leave.

We were warned that Game of Thrones would start spoiling the books in a big way this year, and it has been doing so on a low-level ever since the show began. The most insidious kind of spoiler the show has to offer is the spoiler of omission, and that’s what hit book readers hard last night. Show creators Dan Weiss and David Benioff are aware of how author George R.R. Martin has mapped out the rest of the series, so if they leave something out, even if readers are convinced it’s deeply important, guess what? It’s probably not.

When news first started trickling out that no one had been cast as Griff or Young Griff—the two new characters who travel with Tyrion to Volantis to meet Daenerys Targaryen—book readers got a little nervous. Anyone who has made it all the way through A Dance with Dragons knows that Young Griff is the secret identity of Aegon Targaryen, nephew to Daenerys Targaryen. He’s the son of Dany’s brother, Rhaegar Targaryen, and Oberyn’s sister Elia Martell, and if all had gone to plan he would have sat on the Iron Throne after his father. In the books, this is who Varys and Illyrio Mopatis are plotting to put on the throne in place of the Baratheons. This is the great hope of the Targaryen Restoration. Just like the Skywalkers, there is another Targaryen.

Or is there?

Young Griff’s story line ends up taking over a lot of the narrative in the latest book, but there are those in Westeros who doubt that this Aegon is truly a Targaryen. In a released chapter from Martin’s upcoming book The Winds of Winter, a Dornish knight scoffs at the idea saying, “Gregor Clegane ripped Aegon out of Elia’s arms and smashed his head against a wall. If Lord Connington’s prince has a crushed skull, I will believe that Aegon Targaryen has returned from the grave. Elsewise, no. This is some feigned boy, no more. A sellsword’s ploy to win support.” That’s right—the Mountain definitely murdered Elia Martell’s children, didn’t he? You remember.