Lea, an adventurous and free-spirited thirteen-year-old, lives in idyllic Upstate New York with her academic parents. On the day her family prepares to relocate to Houston, her life takes a drastic turn. Just before their departure, in a tragic misstep, Lea is goaded into a fight with fifteen-year-old Bill. Acting out of frustration, she gets hold of a gun and fires in Bill's direction, causing him to fall into a deep shaft. Without knowing what became of him, Lea is forced to leave with her family. Twelve years later... Lea, who has repressed the memory of those tumultuous events, is an emotional wreck. Her memories of that fateful evening slowly drift back and torment her.

In the near future, a weary Logan cares for an ailing Professor X in a hideout on the Mexican border. But Logan's attempts to hide from the world and his legacy are upended when a young mutant arrives, pursued by dark forces.