Ellaria Sand and her daughter, Tyene, murder Doran Martell and his guard Areo Hotah, seemingly taking charge of Dorne. Around the same time, the other two Sand Snakes, Obara and Nymeria, kill Doran's son, Trystane as he journeys to King's Landing. Ellaria explains her coup to a dying Doran by saying that the people of Dorne are fed up with his weak leadership, citing his inaction against the Lannisters for their many transgressions against Dorne (first the killing Elia Martel and her children many years ago, and the more recent slaying of her brother, Oberon).
Later on, Varys arranges a meeting between Ellaria and Lady Olenna, hoping to broker an alliance between Dorne, Highgarden and Daenerys Targaryen's forces against the Lannisters.
Traveling To Oldtown
With the passing of Maester Aemon, Sam is chosen to travel to the Citadel in Oldtown and train to become the Night's Watch's new Maester. Gilly and Little Sam accompany him, but since women and children aren't welcome at the Citadel, Sam plans for them to stay with his family at Horn Hill. When they arrive they are received graciously by Sam's mother and sister, and decidedly less so by Sam's father, Randyll Tarly.
After his father repeatedly insults Sam during dinner, Gilly defends him and in the process reveals she is a wildling. Furious, Randyll tells Sam that Gilly and Little Sam (whom they believe is Sam's bastard son) can remain at Horn Hill, but Sam must never set foot in their home again. Initially, Sam agrees and bids farewell to Gilly, but quickly changes his mind and decides to bring them with him anyway. On their way out, Sam steals his family's Valyrian sword, Heartsbane.
When they arrive in Oldtown, the Citadel is releasing hundreds of white ravens -- the official herald that winter has come to Westeros. Sam checks in and is allowed to wait in the Citadel's enormous library for the Archmaester, while Gilly and Little Sam must wait outside.
Jorah Mormont and Daario Naharis are on Daenerys' trail, trying to locate where Drogon may have taken their queen. They discover hoof prints and Daenerys' discarded ring, which they deduce must mean she's been abducted by a Dothraki khalasar. That khalasar is led by Khal Moro, who upon learning that Daenerys was once the wife of Khal Drogo, orders she be taken to Vaes Dothrak where she will live out her days alongside the widows of all the dead Khals.
Of course, Daenerys has no intention of growing old in Vaes Dothrak, and when she's presented before the assembled Khals she burns them alive. When she steps from the burning building completely unharmed, the Dothraki immediately swear their loyalty to her. As Daenerys leads the massive khalasar, Drogon returns. She mounts the dragon and proclaims to her new followers that they are all her bloodriders and they will do what no Dothraki have ever done -- ride the wooden horses across the black salt sea, kill her enemies in their iron suits, tear down their stone houses, and give her the Seven Kingdoms.
But first, Daenerys must return to Meereen. She and Daario prepare to depart, while Jorah reveals to her his greyscale infliction. Daenerys orders Jorah to find a cure and return to her.
Tyrion Lannister has been left in charge of Meereen in Daenery's abrupt absence and has managed (with Missendei and Grey Worms' help) to broker a peace with the Slave Masters, who had been using the Sons of the Harpy to disrupt Daenerys' rule. Recognizing they need to do more to secure Daenerys' hold on the city, Varys and Tyrion reach out to the red priests and priestesses of R'Hollr. Many have already been preaching in the streets that Daenerys, as the Mother of Dragons, is their messiah, prince that was promised, Azor Ahia. They would like this to continue, seeing it as an opportunity to cement Daenery's rule over Meereen.
The peace is short-lived, and soon, the Slave Masters return with a fleet to demand the return of their "property" (i.e. the slaves Daenerys freed). They begin a bombardment of the city that is unstopped will quickly overrun Meereen's defenses, at which point Daenerys returns, landing atop the Great Pyramid with Drogon. She agrees to a meeting with the Slave Masters in which she demands their surrender. They refuse, and in response, Daenerys mounts Drogon and, along with Viserion and Rhaegal, lays waste to their entire fleet.
With the Slave Masters and the Sons of the Harpy soundly defeated, Daenerys holds an audience with her new visitors -- Yara and Theon Greyjoy, who've come to offer the assistance of Iron Fleet in return for Daenerys' recognizing Yara as ruler of the Iron Islands and helping them overthrow their uncle, Euron. Daenerys agrees, and after explaining to Daario that he and the Second Sons will remain behind to govern Meereen, she sets sails for Westeros.
Which, for the most part, brings us to where Game of Thrones season 7 will pick up when it premieres on HBO this Sunday at 9:00pm EST.