Why Game of Thrones' Red Wedding shocked us to the core

*Spoilers for Game Of Thrones season 1-3*

Five years ago, on a quiet night in early summer, households the world over recoiled in horror as hit fantasy show Game of Thrones played perhaps its most infamous trump card yet. The Red Wedding.

In episode nine of the third season, fan favourite Robb Stark travels to the castle of fickle allies House Frey for an unassuming wedding; his uncle Edmure being betrothed to one of the vulgar Lord Frey's daughters.

But after the ceremony, during the feast, things take a violent and traumatic turn.

Robb, his mother, and all of their attendant supporters are betrayed by the Freys and the slippery Roose Bolton - and the entire occasion descends into a visceral bloodbath of slaughter.

By the time the dust settles, Robb, Catelyn, and hundreds of Stark soldiers lie dead. The former coldly dispatched with blades to the heart and throat.

Even for a show that had acquired a reputation for violence and shock-factor, this was a moment that left viewers around the world in total shock.

A 'fantastic', terrible twist

From Roose Bolton's sly nod down to his chainmail-clad arm, to Catelyn Stark's chilling, final wail of despair (Michelle Fairley's performance is heart-wrenching), the sense of escalation is extraordinary.

"I remember, as the scene unfolded, thinking variations of 'Oh s***!'," says Chris Slinn, via our Screen Babble discussion group.

"I don't think it was a game changer, because we've seen TV shocks in the past. I don't even think it changed my opinion of the show that much, given Ned's demise so early on.

"But it was a fantastic story twist though - as someone who had not read the books."

Lord of the double-crossing: Walder Frey prepares a toast ahead of the terror to come (Photo: HBO)

Those familiar with the source novels by author George R R Martin knew what was coming, of course. But even they were taken aback by the TV version.

The episode is titled 'The Rains Of Castamere' - the name of the Lannister song of doom that plays prior to the start of the massacre.

Martin has often used the Song Of Ice And Fire book series to subvert heroic fantasy tropes. And this may perhaps be his crowning example.