Updated:11/08/2022 12:53pm cst (Shuri is the new Black Panther not new queen)
Thanks to a source close to Marvel I have the full plot of Black Panther 2 Wakanda Forever. Do not read if you don't want the movie spoiled! You have been warned.
So the movie opens with black panther dying off screen and shuri trying to replicate the heart flower that gives black panther his powers (Remember the flowers were destroyed by Killmonger in BP1). If Shuri could replicate the flower she would be able to save his life but she's unable to do so and T'Challa dies
A year later and the world thinks Wakanda is defenseless without the Black Panther to protect it and other countries are trying to steal the Wakanda vibranium reserves.
We see a French special forces unit attack a Wakandan science center, but SURPRISE all the scientists are actually Wakandian warriors in disguise. (Its hinted that Everrett Ross is feeding Wakanda info so this might be how they were able to set this trap). They take all the soldiers prisoner and drag them in front of the UN.
At the UN meeting the UN asks "how can we trust you guys with vibranium" and the queen is like "how can we trust you? Look at all your soliders we just caught trying to steal vibranium"
Cut to a navy boat, they've detected vibranium underwater but Tlocan warriors attack in response.
The Tlocans have hypnotic singing powers(like the Sirens of myth) to lure the men to jump in the water to their deaths.
Namor then flys up and takes out the one helicopter that almost escapes.
Namor then shows up in Wakanda in front of Shuri and the Queen, gives them the remains of the metal detecting machine and says he needs their help to kill the scientist who made it, to protect both their countries.
Shuri and Okoye somehow trace the machine to Riri Williams and go to try and bring her to safety but someone tips off the cops.
Big escape sequence from the cops, but Talocans show up on the bridge and fight Okoye.
Riri has an experimental Iron Man armor at this point, but gets yanked out of the air by a Talocan cable / spear thing.
Riri and Shuri get taken to Talocan. Okoye gets fired by the queen for allowing Shuri to get kidnapped.
Wakandan Queen goes and visits Nakia(never seen before) and asks her to help rescue Shuri (we later learn this was Black Panther's secret lover).
Namor shows Shuri his magic underwater city and asks her to ally with him but she wont agree to killing Riri so they are at an impasse.
Nakia shows up and saves them both, pissing off Namor.
Namor then attacks Wakanda, drowning the queen!
Shuri starts researching how to defeat Namor, and from the weird Talocan bracelet he gave her she figures out how to replicate the black panther heart flower.
They turn the flower into a magic potion and she drinks it and goes to the ancestral realm expecting to see her mother but instead she sees...KILLMONGER!
He challenges her to not be soft like her brother and devote herself to vengeance. He tells her to kill Namor for killing her mother.
Shuri wakes up with black panther powers and quickly has a suit ready to go.
She tricks the Talocans with a fake metal detecting device, then ambushes them with a special Wakandan ship.
Her plan is to get Namor aboard her ship where she has a room that will slowly evaporate all the moisture out of his body and make him powerless. (Yes, if Namor dries up he loses his strength like in the comics).
Ironheart is flying around in her new armor helping out while the Dora Milaje show off new cgi armor.
The Wakandans are fighting the Talocans on the ship and Shuri gets Namor onto the ship but he is wrecking it up with his vibranium spear so they crash in the desert before all his moisture is gone.
Shuri snaps off one of Namor's leg wings so he cant fly away.
They have a slugfest. Namor impales her on a spear, then stumbles towards the ocean in search of water.
But Shuri manages to push herself off the spear, attack Namor. The ship then explodes setting Namor on fire briefly, he gets seriously burned.
Shuri goes to kill him but then sees visions of all the Wakandans and Talocans she met.
Shuri then sees her mom who tells her to "show him who you really are."
Shuri offers to let him yield, and he accepts. Namor goes back and calls off the Talocans.
Everything wraps up, Shuri's the new Black Panther of Wakanda. She then goes to visit Nakia.
Shuri finally burns her funeral clothes like she had refused to do with her mother at the start of the movie, and feels T'Challa on the wind and is crying
Mid credit scene: We see Nakia introduce her son T'Challa Jr to Shuri.
Also during the movie Everett Ross is arrested for treason by his ex wife Valentina Fontaine.
M'Baku shows up to the coronation site to challenge for the throne, telling the crowd the Black Panther would not be showing up.
Namor confirms he is a mutant
The Talocan people all ingested the heart shaped flower.
Namor has a flashback showing he rescued slaves from Spanish explorers.
Per the Namor flashback, Namor is around 500 years old.