yes opening scene is night king marching to wall with the wildling giant apart of the army
So first scene opens with the Tullys having another dinner. Celebrating the Red Wedding. Walder Frey is alive, hehe no its Arya obviously. She essentially cheers on the entire Frey family and gets them to drink poison during her speech to them that eventually becomes more obvious that shes not who she appears to be. Gives epic ass fucking speech while they all die about leaving a wolf alive was a big mistake and now the sheep are being slaughtered. She leaves the women alive because they dont have any part in it.

Second scene is Cersei over a man painting a giant map of Westeros and Jamie comes in they have a talk about enemies from the north south east and west. Then the Greyjoys show up with a fleet and where Euron offers his navy if Cersei marries him. She refuses but he says something about giving her an invaluable gift upon his return and she wont be able to refuse him.

Quick scene where Bran and whats her face cant remember her name finally show up to the wall, Nights Watch let them in.

Next is a dinner scene with Jon at Winterfell with all the houses of the North where the begin their strategy of fighting the White Walkers. Sansa undermines his authority in front of the houses because she thinks the houses that betrayed Ned should be replaced by loyal familiies where Jon doesnt think children of said traitors should be punished for their mistakes. He gets the two kids of the two houses the pledge allegiance and everyone cheers on Jon for being a cool dude.

Second follow up is Sansa and Jon having a bit of back and forth about what she just did but she makes good points about him and saying dont be stupid like Ned. Ned was noble and so was Robb but it got them killed so be smarter.

They get a raven with a message from Cersei saying bend the knee or die. Sansas like ohhhh no you dont know her jon she crazy, Jons like bitch please we united the north and winter is here with a thousand miles of snow and they are a southern army. They cant do shit.

Baelish tries to woo Sansa quick but shes like I know your moves bud buzz off.

Also hilarious scene between that wildling dude and whats her name (Fuck I should probably rewatch the last season this week names are escaping me). She is training with Tyrions old trainee guy dude and she throws him in a pile of snow and the Wildling guys like with the funniest/creepiest face says "You are a very lucky man" Its funny as hell and will be talk of the episode I gurantee it.

Final notable scene is Danaerys and crew rolling up to Dragonstone where the clean the place up and end up at the giant map that Stannis banged the Red Witch on and she says "Sha'll we begin?" To Tyrion and cue credits and epic music.

Sam -> Yeah he finds a book that says underneath Dragonstone is a giant mine of dragonglass they can use to fight white walkers

Ditocorto -> Yeah for sure. No big bits of information are revealed its more of a setup scene id say for later episodes illustrating their relationship. Brienne interrupts them and asks why is he still there (he leaves at this point) Sansa mentions that without Baelish we wouldnt of taken Winterfell. Hes earned his right to stay.

Its essentially Petyr trying to get into her head (perhaps to take winterfell for herself) and shes having none of it.

Tormund -> him and the wildlings are being sent to what Jon believes will be the first line of defense against the white walkers. I cant remember what castle was mentioned they will be stationed at but its at the wall close to the sea.

oh also i forgot the big part with Sam being at the Maester Citadel. Theres like a cool scene where it compares him cleaning up old mens shit and feeding porridge to everyone else while he tries to sneak into the restricted zone to get restricted books. He eventually finds a book that says Dragonstone has an underground mountain full of Dragonglass to be mined.

Cersei thinks destroying all the houses against her is gonne be easy (shes getting really cocky) and Jaime is being more realistic. He mentions that now winter is here we need food and shelter for them and the horses which we dont have stuff like that. Hes the head of the Lannister military so he gives her military advice.
Jaime insists they talk about Tommen killing himself and they are the only Lannisters left. Cersei calls Tommen a traitor and thats the end of it.
she refuses Euron because of his reputation of betrayal.

If its not Wun Wun it reallyu looks like him. They zoom right into his face. Same hair same build. Hes not the only giant as well theres maybe three more behind him. I remember what you mention with Wun Wun so it might not be him but they deffinitely imply that it is.
He has a missing eye as well. (did wun wun get an arrow to the eye? Cant remember)