So, what I currently have for the overview for the Season:
Season 4 Overview
Episode 1: First Contact for Círdan and the rescue of Maedhros
The Host of Fingolfin is encamped on the north end of Lake Mithrim, while the Host of Fëanor is encamped on the south. They are uneasy with one another, as the Fëanoreans never thought to see the elves they'd betrayed again. Fingolfin has learned of his (half-)brother Fëanor's death, and Fingon has learned that his (half-)cousin Maedhros is missing. The Fëanoreans are stuck and Maglor is not a decisive leader.
Círdan makes first contact with the Noldor. After an initial language barrier, they are able to communicate, and Círdan is both surprised and happy to learn that these elves have come from Valinor and are the descendants of the elves they said goodbye to ages ago. They ask after Finwë and Olwë, and want to know how and why the Noldor have come back. The Noldor dissemble. No one mentions the Kinslaying. They claim they have come back to fight Morgoth, and everyone agrees that is a good thing.
Morgoth sends a cloud of darkness to cover the land, so his evil creatures can move about freely in the sunlight. Seeing this, Fingon gets an idea and departs with a harp and a bow.
Círdan learns that some of the Noldor are descendants of Olwë, and invites them to come to Doriath as kin of the king (Elwë). Finrod cautions Angrod to behave diplomatically and speak as little of the Fëanoreans as possible. Does Galadriel go or stay? Who leads the trip? (Celeborn? Círdan? Or...?)
Meanwhile, Fingon reaches Thangorodrim and discovers where Maedhros is hanging out of reach. With the help of Thorondor, he manages to rescue his friend. A weakened and one-handed Maedhros is brought back to the camp.
Fingolfin reforges Ringil?
Telchar makes Narsil? Eöl reintroduced?
Episode 2: Diplomacy
Círdan's group reaches Doriath and is admitted to Menegroth. Thingol meets Angrod (and...?) and welcomes him as kin and asks about Valinor. Angrod gives an extremely whitewashed version of the story thus far. He tells of Morgoth's wrongs, but sorta skips over the rebellion of the Noldor. He does not go so far as to call the Noldor emissaries of the Valar.
Thingol is less that satisfied with this tale, and concerned when he learns of a new standing army in Beleriand (even if it is between him and Morgoth). Thingol declares Doriath off-limit (except by invitation) and cautions the Noldor not to impinge on Sindar lands. Angrod considers his diplomatic mission a success - he's established kinship and friendship with Thingol, and gained permission for the Noldor to settle Beleriand.
Maedhros recuperates; learns how to handle a sword and do other mundane tasks one-handed.
Celeborn and Galadriel have a getting-to-know-you conversation. She is young and impetuous, and he is older and more likely to keep his thoughts to himself, but there is the first spark of mutual respect and interest between them.
Angrod returns to the camp in the north. Finrod is pleased with how it went, but when Angrod presents Thingol's words to the gathered Noldor leaders, Caranthir has an immediate and violent reaction. He questions Angrod's authority to speak for all the Noldor, and considers Thingol's welcome too cold. Maedhros, who is still recovering but hale enough to attend the meeting, physically removes Caranthir and speaks more diplomatically, dismissing both Caranthir's concern and Thingol's authority outside his own borders.
The Noldor are left with a question of who will lead them now - are they destined to fracture apart?
The bad guys are very much alarmed by Thorondor's involvement in Maedhros' rescue. Morgoth suspects that the Second Children have awoken?
Episode 3 - Crowning the High King
More Sindar-Noldor interactions
Maedhros gets his house in order. He rebukes Caranthir for the unwise outburst, and explains how that cost them. They need the Host of Fingolfin if they are going to fight the armies of Angband, and he's not going to let his brothers cost them that fragile alliance. Curufin has some things to say about Fingon and Angrod. Maedhros says that now that he's back, he's in charge, and they'll obey him. Amras and Maedhros have a private conversation.
The Noldor have a convocation(?) to discuss leadership. It is expected that the Host of Fingolfin will select Fingolfin and the Host of Fëanor will select Maedhros and there will be a permanent split into two separate people. Maedhros surprises them all (well, not Maglor or Fingon) by declaring Fingolfin the heir of Finwë and thus ceding his own claim as his father's heir. [Ie, he'll never use the name Nelyafinwë again....] Fingolfin is acclaimed as High King by all the Noldor
Fingolfin gives the Noldor some kingly advice about establishing themselves in Beleriand and staying on good terms with the Sindar.
Maedhros decides that the Fëanoreans will need to go to the East. It's the area that's one of the hardest to defend from Morgoth, and it's far away from everyone else. He says goodbye to Fingon before they go, and they have some meaningful conversation about the hand that was cut off and the rescue that was supposed to be a mercy killing.
Episode 4 Of Beleriand and its realms. Lots of building.
Galadriel goes to Doriath to become Melian's pupil. Círdan returns to the havens.
Eöl is outraged at his new Noldor neighbors.
Death of Norn?
Establish courts and see the first Noldor/Sindar interactions. Rumors about the arrival of the Noldor spread through the Sindar.
Morgoth (or Sauron) finds Men in the East
Episode 5 - Feast of Reuniting in Nevrast
Turgon's court hosts Fingolfin's party. Attendees include: Maedhros, Maglor, Beleg, Mablung, all of the princes of the Noldor from Fingolfin’s camp, many Sindar, Círdan, Celeborn. NOT attending are Thingol, Eöl, the other sons of Fëanor, any dwarves (Telchar? Norn?)
Daeron and Maglor duet? (or more dueling banjos?)
A 'false peace' exists, as the Sindar don't know the truth about the Noldor, and the lack of activity from Angband makes some people consider the sun to have conquered Morgoth's orcs. During the Feast, Finrod makes his statement about never marrying, and an oath he will one day swear. Also, Celeborn and Galadriel have a heart-to-heart while looking out over the ships in the harbor. Galadriel reveals some of the darkness that is over the Noldor, but focuses on the personal tragedy of having lost her mother. Celeborn is a good listener (and remembers the loss of his own family to the Hunter?)
Orodreth meets a lovely Sinda lady.
Episode 6 - The truth of the kinslaying comes out
Galadriel tells Melian the truth of the Darkening of Valinor - that Morgoth killed the Trees and killed Finwë and stole Fëanor’s silmarils.
Melian shares the pertinent parts of this with Thingol, who is bothered, but does not think it too serious to continue on in friendship with the Noldor (who after all have a common enemy).
Eöl requests permission to call Nan Elmoth his own. Thingol says he is free to choose any land outside of Doriath, but Nan Elmoth belongs to him.
Orodreth marries a lovely Sinda woman whom he met at the Feast at the Pools of Ivrin.
When Thingol confronts Angrod about his less-than-full tale of the flight of the Noldor, Angrod confesses the Kinslaying. After all, he has no reason to protect the Fëanoreans from the truth of their own misdeeds.
EDIT: Celeborn and Galadriel plight their troth (declare their love to each other, whatever).
Episode 7 - Thingol's ban
Eöl makes swords with the intent of purchasing what Thingol will not give freely. Telchar sees these swords and is disturbed by the darkness of them.
Thingol bans the speaking of Quenya and wearing of jewels, saying that those who do so are kinslayers unrepentant. Círdan and Thingol mourn the death of Olwë.
Fingolfin as High King accepts the terms of the ban. He finds it more important to keep peace with their new neighbors than to protect their own culture. He’s fine with speaking Sindarin and who needs to wear jewels, anyway?
Episode 8 - The Dagor Aglareb!
Gothmog unleashes a huge army of orcs on the north.
All the good guys must unite to fight back the assault.
Forgiveness so they can work together to protect their lands is wise.
Episode 9 - Ulmo's intervention
Fingolfin sets up the Siege of Angband to last forever.
Finrod and Turgon receive dream messages from Ulmo warning that the peace will not last.
Morgoth and/or Sauron returns from the East and debriefs
Episode 10 - The Petty-Dwarves
Finrod visits Galadriel in Menegroth and seeks Thingol’s help.
Thingol tells him about the caves of Narog and sets up a meeting with the dwarves to aid him. Petty-dwarves driven out of Nargothrond (by dwarves)
Ulmo shows Turgon the vale of Tumladen.
Celegorm, Curufin, and Caranthir ‘accidentally’ hunt Petty-dwarves in the East.
Amras is anti-social on Amon Ereb.
Morgoth makes dragons.
Episode 11 - Hewer of Caves
Finrod works on building Nargothrond. Dwarves name him ‘Felagund’
Caranthir meets the dwarves of the Blue Mountains; luckily, they’re okay with killing the faithless petty-dwarves.
Turgon builds Gondolin in secret. (Aredhel stays behind with Idril in Nevrast?)
Círdan rebuilds the Havens with the help of the Noldor. Finrod builds Barad Nimras to guard the sea. Círdan expresses his desire to continue to work with them and help them in their times of need despite the Kinslaying. He does not want to do Morgoth’s work for him.
Episode 12 - The Hidden City
Turgon moves his people from Vinyamar/Nevrast to Tumladen in secret.
Galadriel marries Celeborn.
Nargothrond complete. Young Zirak presents the Nauglamir to Finrod.
Villains make a cryptic reference to Men.
Episode 13 - A Dragon Unleashed
Young Glaurung escapes Angband and devastates the north (particularly Ard Galen). Angrod and Aegnor fall back to Dorthonion. Fingon fights Glaurung back to Angband.
Turgon stays safely in Gondolin and does not fight.
Thingol stays safely in Doriath and does not fight.
Telchar makes her last work - the Dragon-helm - and gifts it to Azaghâl.
I realize I have not mentioned Lúthien at all, and Eöl is only clumsily worked into the story.
I was almost thinking that she likes him (she seems like she would find the positive in bad people), or has a premonition that he has a role to play and convinces her father to complete the bargain.