This is a news story about a future episode of Game Of Thrones. If you do not want to know anything at all about what's coming, it's best that you don't read this news story. Caveat: you're probably safe here if you've read the books. But still, proceed at your own risk.
The story, then! Following his pivotal "Blackwater" in Season 2, director Neil Marshall is returning to Game Of Thrones. Our source close to the production - who we shall name "Ned" in honour of the dear departed Sean Bean (and the '90s indie band) - tells us that Marshall has been asked back for another enormous chunk of ice and fire, in this case the violent finale to Season 4. The episode, Ned tells us, takes place "at The Wall, with Mance Rayder".
Readers who've got as far as A Storm Of Swords will recognise this as The Battle Of Castle Black, where King-Beyond-The-Wall Mance Rayder leads his force of Wildlings, Thenns and mammoth-mounted Giants against the forces of the Night's Watch and King Stannis Baratheon. The scrap lasts several days, and is the event that leads to Jon Snow becoming leader of the Watch.
In the book, former blacksmith Donal Noye plays a significant role in these events, but as he apparently remains uncast in the series, expect some tweaks to the way the carnage unfolds onscreen. Although with or without Noye, we could probably have assumed as much anyway.
Marshall was airlifted in at extremely short notice to direct Blackwater, but Ned tells us that the director has a much longer lead-in on this occasion, already moving backwards and forwards between London and Northern Ireland to prep the episode, which shoots later in the year. Game Of Thrones' fourth season will premiere on HBO in the first half of 2014.