Lucina is born the daughter of Chrom, the prince of the Halidom of Ylisse, in a world that is doomed to fall to despair. She nevertheless fights tirelessly to resist Grima, the Fell Dragon, who is determined to destroy the world, even after the conflict claims her father's life. When all hope finally seems lost, she borrows the power of the Divine Dragon Naga to travel back in time in a desperate bid to rewrite history.
She arrives in an Ylisse of the past and, with her late father's sword Falchion in hand, works to help the past version of her father and his tactician Robin overcome Grima's servant, the dark mage Validar. Through the bonds Lucina and her allies forge, they are able to win the day and lay Grima low. What becomes of her after that is a mystery.
Some believe she returns to her original time, while others say she remains in the past and lives out the rest of her days in peace.