Wight Hunt

The mission to capture a wight is undertaken by the King in the North Jon Snow and his allies in order to provide proof to Queens Cersei Lannister and Daenerys Targaryen of the existence of the wights and their masters, the White Walkers, led by the Night King, who had risen again after 8,000 years.

King Jon was accompanied by his principal advisor, Ser Davos Seaworth, wildling chieftain Tormund, Robert Baratheon's bastard son and Davos's friend Gendry, and Ser Jorah Mormont of Daenerys's Queensguard, traveling to Eastwatch-by-the-Sea from Dragonstone. There, they also joined forces with the Brotherhood Without Banners, including Lord Beric Dondarrion, Thoros, and Sandor Clegane, which had marched north from the Riverlands to help play a part in the war against the White Walkers, having been guided by visions.

The mission
The mission will be depicted in the sixth episode of Season 7.

In the books
In the A Song of Ice and Fire novels by George R.R. Martin, such a mission has not occurred. The timeline of the TV show has surpassed that of the book series, so it is unclear if the mission or an equivalent event will occur in either of the forthcoming novels, The Winds of Winter and A Dream of Spring.