A Storm of Swords, the third book in George R.R. Martin's epic A Song of Ice and Fire series, is one of the busiest books in the entire franchise to date. The novel, told through the perspectives of 10 different point-of-view characters (excluding Chett and Merrett Frey, the one-off narrators of the prologue and epilogue respectively), continues the story of the War of the Five Kings, and is filled to the brim with the most notorious plot twists in the series, including the infamous Red Wedding.
When tasked with adapting A Storm of Swords for A Song of Ice and Fire's TV iteration, Game of Thrones, the creative team decided to tackle the book's scale by splitting it up into two different seasons. As such, season 3 mostly tells the story of the first half of the book, with the Red Wedding acting as the climax, while season 4 primarily brings the second half to the small screen, focusing on the aftermath of the murder of King Joffrey Baratheon (Jack Gleeson) at his own wedding.
Plenty of changes came along with this reshuffling of A Storm of Swords. One subtler tweak comes in the form of the order in which the story is told. In fact, the cliffhanger final chapter of A Storm of Swords (excluding the epilogue) actually takes place towards the middle of Game of Thrones season 4, and its early arrival helps foreshadow future storylines that now come afterwards.

The ending of A Storm of Swords
The final chapter of A Storm of Swords takes place in the Eyrie, the ancestral seat of House Arryn, and is told from the perspective of Sansa Stark (Sophie Turner). Sansa attempts to build a snow replica of her home, Winterfell, and eventually, Petyr Baelish, also known as Littlefinger (Aidan Gillen), comes to join her. After telling Sansa that she is even more beautiful that her mother Catelyn (Michelle Fairley), the one woman Petyr has ever loved, he kisses her, much to Sansa's dismay.
The two are interrupted by Robert Arryn (Lino Facioli), who proceeds to destroy Sansa's snow Winterfell, causing her to grab his doll, accidentally ripping it in half. Robert then suffers a seizure, and Sansa is brought before her aunt Lysa Arryn (Kate Dickie), Robert's mother and Petyr's wife.
To Sansa's shock, Lysa does not berate her for causing Robert's seizure, but instead, she accuses Sansa of trying to steal Petyr, having witnessed their kiss. Lysa is prepared to push Sansa through the Eyrie's deadly Moon Door, until Petyr arrives to talk her down. Lysa reminds Petyr of how she poisoned her first husband, Jon Arryn (John Standing), for him, and framed the Lannisters as his murderess in a letter to Catelyn, and Petyr reminds the unwell Lysa that he's only ever loved one woman..."Only Cat." Petyr then pushes Lysa through the Moon Door, killing her.

Game of Thrones moves up Lysa's death
This sequence plays out mostly similarly in Game of Thrones as it does in A Storm of Swords. However, unlike in the book, Lysa's death takes place towards the middle of the season, ending the seventh episode, "Mockingbird." In fact, Petyr and Sansa appear in the following episode, "The Mountain and the Viper," continuing their seasonal storyline beyond the ending of Martin's third novel.
In moving Lysa's death forward, Game of Thrones uses it to foreshadow another death, which now takes place later on in the season. In the season finale, "The Children," Tyrion (Peter Dinklage), recently rescued from his impending execution, stops by the Tower of the Hand to confront his father, Tywin (Charles Dance). There, he finds his former lover, Shae (Sibel Kekilli), whose recent betrayal helped cement Tyrion's fate, having learned that she is now sleeping with Tywin. Tyrion and Shae fight, and he strangles her to death, a decision which show Tyrion instantly regrets.
In positioning Littlefinger's murder of his lover before Tyrion's, Game of Thrones allows the two killings to parallel each other. Littlefinger and Tyrion are ultimately similar characters, with both men using their wits to maneuver the shady politics of King's Landing, both often find themselves underestimated, which they use to their advantage, both end up connected to Sansa Stark, and both end up murdering their lover.
Given that Tyrion is the more prominent character of the two, repositioning these two events so that Lysa's murder takes place in the episode after Shae's betrayal of Tyrion but before her death, helps plant the theme of killing one's partner in viewers' minds, potentially teasing what Tyrion will do a few episodes earlier.
For more from the world of Westeros, make sure to catch House of the Dragon season 3 when it premieres on HBO and HBO Max on June 21.
