The full story
This cosmic origin story is set in 1995 and features substantial revelations about the Kree.
Vers is a warrior of Starforce, the Kree Empire's elite military unit. She is powerful but inconsistent, plagued by dreams she cannot explain and emotions her commander Yon-Rogg tells her to suppress. Her mission against the shape-shifting Skrulls goes awry, and she ends up crashing through the roof of a Blockbuster in Los Angeles.
S.H.I.E.L.D. Agent Nick Fury—with two working eyes and considerably less cynicism than his future self—investigates the alien crash. He discovers that Vers is not Kree. She is Carol Danvers, a human Air Force pilot who was presumed dead six years ago. The Kree did not save her but rather abducted her.
The Skrulls are not invaders but refugees. The Kree have been systematically exterminating them, and the Skrulls have been searching for a new home. Their leader Talos wants to find his family. The shapeshifting enemy Carol has been fighting during her Kree service are actually victims.
Carol's memories return piece by piece. She was a pilot, flying experimental aircraft designed by Dr. Wendy Lawson—actually a Kree scientist named Mar-Vell who defected to help the Skrulls escape. When their plane was shot down, Carol destroyed Mar-Vell's light-speed engine to keep it from the Kree. The explosion infused her with the energy of the Tesseract—the Space Stone.
The Kree found her, wiped her memory, and turned her into a weapon against the very people Mar-Vell died trying to save.
Carol unleashes her full power. Yon-Rogg spent years teaching her to fight with her hands, to suppress her emotions, and to limit herself. "I have nothing to prove to you." She goes binary—accessing full cosmic power—and single-handedly stops a Kree bombardment, destroys missiles in the atmosphere, and sends Ronan the Accuser retreating.
Carol leaves Earth to help the Skrulls find a new homeworld, giving Fury a modified pager for emergencies only. She will be gone for decades, but she leaves behind the inspiration for Fury's "Avenger Initiative" (named after Carol's old callsign).
The mid-credits scene connects directly to Endgame: the remaining Avengers study Fury's pager, the signal stops, and Carol appears. "Where is Fury?"