It sounds like you're referring to the release of Game of Thrones Season 3 — but instead of just summarizing it, you want me to develop a new story based on that era.

He burns the scroll — but Mira memorized it.

“We already know,” he says. “The Lannisters are dead men walking. We’ve chosen a new dragon.”

Before Mira can reach the Brotherhood Without Banners, she’s intercepted by — a ruthless sellsword who wants the R5 scroll for himself. He explains: R5 isn’t just a military order. It’s a financial weapon. If the Iron Bank learns that the Lannisters plan to wipe out the Starks and Boltons without a formal declaration, they’ll call in all debts, triggering a collapse of the Seven Kingdoms.

Mira doesn’t know it yet, but R5 is a Lannister contingency plan: — but only after the Red Wedding. The “fifth raven” refers to a spy inside Robb’s camp confirming that Jeyne Westerling is not pregnant, and that Bran and Rickon are presumed dead.

During the chaos of Season 3, a mysterious coded message — designated R5 — falls into the hands of a lowborn scribe in Harrenhal. It contains a secret that could save or doom the Starks, the Lannisters, and the last Targaryen. Story:

But the Hound laughs it off. “Girl, every day is a massacre.”

Mira escapes again but is captured by just before the Red Wedding. Roose himself reads R5 and smiles: “Tywin writes as if I needed his permission to kill wolves.”