Warning: This contains spoilers for Game of Thrones season 7 episode 6 Beyond the Wall episode.
Just when we were all feeling so smug about having cracked the code on the old Ice and Fire thing - well, obviously, it means Daenerys and Jon will come together, one way or another - along comes a total Game of Thrones head-spinner to make us think again.
The final moments of the last-but-one episode of the last-but-one season on Monday left fans reeling (or at least those fans who hadn't already watched the episode thanks to HBO's inadvertent leak in Spain and Sweden five days earlier). But if you're on a dial-up 64k modem or have a job and and aren't among those who've already watched it, you probably should stop reading until you've had a chance to see for yourself.
What if A Song of Ice and Fire is not a reference to the humans in Game of Thrones at all, but to the dragons?
We know Drogon and his two siblings provide the fire. But what if one of them were killed by the Night King and resurrected - would he then breathe ice? How cool (literally) would that be?
That was the tantalising and frankly terrifying prospect with which we were left as the sun set on this episode. A dragon has been raised from the dead. What happens next will upend everything.
Dany had flown her three dragons into battle against the army of the dead, saving Jon and his intrepid band when all seemed lost (admittedly, something of a regular occurrence these days). But as the dragons circled overhead, laying waste to the dead and the ice alike, the Night King launched an icy spear. It hit one of the dragons, which plummeted to Earth in a spume of blood and guts and flame before sinking beneath the icy waters. What a massive crossbow had been unable to achieve, an icy pole managed at one stroke.
Ten minutes later, we returned to the land beyond the Wall, to find the army of the dead-undead dragging massive steel chains as they hauled the dead dragon out of the water. Where did they get those chains, you might have asked - it's not as if they could just pop out to a Super Cheap Auto up there, is it? But that would have been like asking where had Jon and co found the wood to make that fire earlier in the episode, or how did Bronn manage to hoist an armour-clad Jaime out of the lake with just one hand last week. Such questions are not welcome here, doubters. Be gone with you!
With said beast hoisted clear, the Night King laid a hand upon his scaly brow, and after a brief moment an eye opened. It was blue. An undead dragon was born.
As set-up for the end game, it could hardly have been better. Now, presumably, we can look forward to the sight of the Night King riding into battle above King's Landing on the back of a dragon, spewing ice upon all that stands in his way. Winter is coming indeed - from ground and from the air. Here's hoping the undead don't know how to sail, but you wouldn't count on it.
The Watchers on the Internet Wall tell us the dragon-that-was-dragged-up is Viserion, but only a mother can tell them apart, and Dany hasn't yet said for which of her "children" she is grieving.
One thing is almost certain, though: she is going to have to kill one of her darlings if this battle is to be won. Even if he is dead already.