Dar Benn is the regular leader of the Kree, no side factions or anything like that. In flashbacks, she witnesses Carol attacking the Supreme Intelligence and that’s her villain origin story. The Kree refer to Carol as “The Annihilator” or something very similar, and she does not like the name.

Dar-Benn has one bangle, Kamala has the other. No idea how she has it. She’s using it to power a weapon, but she needs both bangles. There’s a funny line where Dar-Benn demands to know how Kamala got such an ancient and powerful artifact and Kamala responds “my grandma sent it to me in the mail.” It wasn't explained in the rough cut that I saw, but almost immediately, Monica, Carol, and Kamala begin switching places every time they use their powers. Monica is working on a space station, SWORD’s “The Peak” headquarters with Nick Fury; Kamala is at home, and Carol is trying to sneak into a Kree/Skrull peace summit because she doesn't trust Dar-Benn, who is the leader of the Kree.

So Carol starts fighting Kree soldiers, and then begins switching with Kamala and Monica, and the Kree soldiers start switching with her. So at one point, Carol is on The Peak with Fury, while Kamala is at the peace summit, and Monica is fighting Kree soldiers in the Khan living room while the Khan family tries to hit them with brooms/fight them/runs around screaming. Very fun sequence. At the end, everyone - Fury included - ends up in the Khan living room, except Kamala. That ending scene in the Ms Marvel show is a direct shot from The Marvels.

Carol leaves the house and tries to fly off, but they switch again, and suddenly Kamala is falling out of the sky, and Fury tells Monica she has to fly and save her; Monica resists, because she doesn't know how to control her flight yet, but Fury yells, "C'mon, Black girl magic!" and Monica flies up to save Kamala. However, she loses control on the way down, everyone is screaming, and at the last second, Monica and Carol switch and Carol is able to stop before they hit the ground. Fury screams as they are dropping and at the last second "AHHHHH - oh it's just Carol."

Anyway. Carol, Monica, and Kamala go off to investigate Dar-Benn, sticking together because they can't control the switching every time they use their powers. It's really not explained, except for some allusion to how their powers are all similar or variations of each other?

They discover that Dar-Benn is using a new weapon to create unstable portals that steal the resources (water, air, sun) of whole planets, and she sends the resources to the destroyed Hala to rebuild it. She's so far destroyed one planet at the beginning of the film for it's atmosphere, she destroys the second at the Kree/Skrull peace talks, then she goes after Aladna to steal their water.

Carol has already been to Aladna and is reluctant to go back because she is the princess, married to Prince Yan in an accidental diplomatic mistake. Everyone on Aladna sings as a way of communicating. Brie sings. She has a lovely voice but it's an awful sequence...

They realize the planet is Dar-Benn’s next target and go there to get help fighting her, to protect the planet and stop her rampage. The girls bond well before this in a montage on Carol’s ship on the way to Aladna. Monica helps Carol get used to working with Kamala - Carol yelled at Kamala in an early scene because Kamala froze up in a pivotal moment, Monica reminds Carol that Kamala isn’t a soldier. Monica and Carol also have conversations about how Carol left and never came back. All three kinda work through their issues. It’s later revealed that Carol did indeed come back and visit Maria, more than once.

Prince Yan doesn't have a crush on Carol, he and Carol are married. But Carol and Prince Yan seem to have a very platonic friendship and mutual respect. Nonetheless, Carol is very embarrassed about it and reluctant to visit Aladna, it's played like she didn't understand the customs and accidentally got diplomatically married to the Prince at some point in the past. The citizens of the planet worship her as their princess. Prince Yan himself is cool though, and isn't played as a goofy trope, though. But it is a whole awkward sequence that goes on for entirely too long. Monica is weirded out by the whole situation; Kamala is excited. Monica asks if Kamala is going to put this in her Captain Marvel fanfiction and Kamala says yes.

Anyway, Carol realizes that she's going after every planet Carol has ever called Home, in an act of revenge. Earth is the last part of the plan. Meanwhile, Fury takes the Khan family up to the space station to keep them protected so he can monitor the situation from there.

A side plot on the space station with Fury: some techs find weird eggs inside all the space station machinery. They're all really worried about some sort of alien attack. The eggs hatch and it's revealed they are newborn Flerken kittens. Chaos ensues on the space station.

Later, the space station is damaged by Dar-Benn when she attacks Earth in the climax. There are not enough escape pods to get everyone off the station before it crashes. Fury comes up with the idea of feeding everyone on the station to the Flerken kittens, then putting all the kittens on the escape pods, and getting to Earth safely that way. It's amusing/bizarre, and the whole film has this really weird tonal clash between a standard marvel movie and something goofier, like Guardians.

Monica and Carol go to Hala, and it is raining for the first time on Hala and the surviving Kree are celebrating, because Dar-Benn brought atmosphere and water back to them. Carol realizes that the Annihilator is accurate from their perspective - she destroyed this planet and the survivors are struggling and she’s a great villain in their eyes, and she has a moral reckoning. Stopping Dar-Benn means destroying Hala all over again. Monica gives her a little bit of a pep talk that basically amounts to “We can’t save everyone, we have to let Hala be destroyed again.” Carol re-affirms her desire to stop Dar-Benn.

In addition to Dar-Benn destroying planets, her creation of portals makes the universe unstable, increasing the likelihood of an incursion, which is another reason they have to stop her. An incursion happens in the climax - Carol fights Dar-Benn while Monica and Kamala try to fix the incursion. Monica ends up flying through this “tear” in the universe and fixes it on the other side, and ends up stuck in that other universe."