Vers (played by Brie Larson) is a Kree warrior, her mentor and trainer is Yon-Rogg (Jude Law). The Kree are at war with the Skrulls, who are evil shapeshifters led by General Talos (Ben Mendelsohn). The war against the Skrull take Bree, Yon-Rogg, and the rest of their crew to planet "C-53" (aka "Earth," circa 1995) where Vers begins to realize that she may have had a life among the humans. This begins a series of reversals and a deeper understanding of herself. And of course she meets a young Nick Fury (Samuel L. Jackson, de-aged for the part) and Phil Coulson (Clark Gregg, also de-aged).
The movie is charming, funny, and entertaining - and introduces us to a hero with powers on par with Superman (even if that's a DC character). But there are a lot of frustrations about the movie: the biggest and most obvious being that "Avengers: Endgame" is already in theatres, and it feels like all this is just back-story before "Endgame" landed. "Hey, none of the current Avengers can challenge Thanos, we need to fill that slot - time to put 'Captain Marvel' in the microwave to thaw her out." "Oh, and make her a woman - we need more of those." (Mar-Vell has been both genders over the years: they chose the more politically correct one ... a bit late at 20 movies into the franchise.) My second biggest frustration is that Jackson is 70 years old, and he damn well runs like it. They can fix his face in post, but they should have got a body double for the two scenes where he "runs" (more of a crooked jog). Finally, this just isn't their best movie. Yeah, it's fun, but it's not deep, and more than anything it just feels like prep for "Endgame" rather than its own movie.