Basically for context Madeline (the red haired girl) climbs up Mount Celeste, a mountain with known phenomenons and danger inside it, it’s no ordinary mountain. The reason she is doing this is because she has no motivation to continue her life and is dealing with feelings of anxiety and depression, so much that she’ll climb a mountain that’s dangerous and push herself against her limit
Madeline discovers that the mountain is hiding mystical secrets herself, as purple haired red eyed version of herself appears out of a mirror in her dream, but it’s actually all real, and she keeps following her to make her leave the mountain and go back home, to forget about this dangerous place and leave, but she does it in extreme ways that hurt Madeline
Madeline tries to ditch her and think that they’d be best off separate from each other. This isn’t true though, because the purple haired version of her self is a representation of the part of herself that she despises
But in the end, Madeline realizes that the part of herself that she hates and has tried to hurt her is actually just really scared, and that she’s just a part of her that came to become separate because of the mountain, and then they hug and reunite, and climb back up the mountain again
It’s a fantastic story