After escaping from the dungeons of Arendelle, she secludes herself in the Mountains, away from the Kingdom and all the memories she had. During her isolation, she searches for a way to melt the ice and end the winter she caused. When she comes across a familiar face, she comes to a full realization of what she has caused and vows that she will avenge her in anyway she can.
This story takes place in a time where Anna died before making it out to the fjord and Elsa didn't see her death.