All around the world right now, A Song of Ice and Fire fans are scratching their heads and flicking through their copies of A Storm of Swords, wondering what on earth they just watched.

In true George R. R. Martin fashion, tonight’s Game of Thrones episode, ‘Oathkeeper’, ended with one hell of a curveball – only this time, it wasn’t something from the book.

D. B. Weiss and David Benioff have made a series of changes from the books – most recently, and controversially, transforming a consensual sex scene into a rape – but this is the first time we’ve seen something brand new. And hell, it was exciting.

Rounding off the episode in superb, boundary-pushing style – and rendered in astonishingly good CG – were the White Walkers. For the first time, we caught a glimpse of their home (imagine a snowy version of Minas Morgul) where it was revealed that the Craster’s sons are not being munched on but transformed into Walkers themselves. Meaning these dudes aren’t just mindless zombies; they’re clever, they’re organized and they’re building an army, one bastard baby at a time.

Back down south, we discovered the identity of Joffrey’s murderers: Littlefinger and Olenna Tyrell. In one scene, Littlefinger – firmly sticking with that part Irish/part pirate accent – did what he does best, hamming it up and lecturing Sansa about the nature of the game. Though his reasons for murdering Joffrey seem a little confused, there was a great moment when Sansa asked him what he wanted, to which Littlefinger coolly replied: “Everything.”

Indeed, ‘Oathkeeper’ was quite the episode for snappy lines. Elsewhere, Jaime visited Tyrion to ask if he really bumped off Joffrey, and their edgy, brother-bants repartee culminated with Tyrion’s question: “Are you really asking if I killed your son?” (marking, of course, the first time that the brothers have openly admitted Joffrey’s true parentage).

In typical fashion, the Tyrells worked their magic on Tommen, with Margaery visiting the wee lad in his bedroom to dangle herself in front of his hormonal tween eyes. We also finally got to see a bit more of Daenerys’ ferocious side as she decided to teach the slave masters of Yunkai a lesson, namely by nailing them to wooden posts. Ouch.

At the heart of the episode, though, was Jaime’s gifting of his Valyrian blade to Brienne and sending her off to safely retrieve Sansa. Seemingly – and a little problematically – back in the “good guy” camp after his assault on Cersei last week, Jaime was all honour this week, defending Tyrion and keeping the oath he made to Catelyn Stark to protect her daughters. Of course, everything Jaime does is tangled up in his relationship with his sister, and we couldn’t help but wonder if he was sending Brienne to save Sansa solely to piss off Cersei.

As the episode neared its end, we moved north and saw Bran & co. taken captive by the Night Watch traitors at Craster’s keep. Leading the pack was Burn Gorman’s bombastically evil Karl Tanner, who demonstrated that Game of Thrones can get away with seriously silly characters if the actor’s performance is committed enough.

With Bran holed up at Craster’s, and his brother Jon on his way there to kill the Night Watch traitors, could we be about to witness a Stark brother reunion? Something tells us the series might be too cruel to deny us that. Then again, with changes from the book coming in thick and fast, who knows…

Aired on Monday 28 April 2014 on Sky Atlantic.

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