A tactician, Mark, wakes up in a house on the Sacae plains. A teenage girl introduces herself as Lyn of the Lorca, a tribe of nomadic plains dwellers. Suddenly, bandits attack; Mark aids Lyn, who, with a sword, fights them off. The next morning, she decides to travel with Mark, to avenge her dead parents and the rest of the Lorca tribe, who were killed by bandits.

In the town of Bulgar, Lyn meets the womanizing cavalier Sain and his more serious partner Kent, both knights of Caelin, a territory in Lycia. She is disgusted by Sain's nature and leaves the city. Then, more bandits arrive to attack Lyn, and the knights go to their aid. After the battle, the knights inform Lyn, whose name is revealed to be Lyndis, that her mother Madelyn was the daughter of Hausen, the marquess of Caelin, making Lyn next in line for the throne. The bandits were sent by Lundgren, Hausen's younger brother, who aspires to be marquess. Lyn is a threat to this, so her life is in danger; the group decides to go to Caelin.

Lyn unsheathes the Mani Katti.
Lyn takes the group to a shrine to pray for a safe journey. There, her party defeats bandits seeking to steal the sacred sword, Mani Katti. As thanks, the caretaker of the shrine allows Lyn to hold the Mani Katti and pray. She draws it from its sheath, meaning the sword's spirits have chosen her. Since Lyn is the rightful owner, the priest allows her to take the sword.

Lyn sees her friend, the shy pegasus knight Florina, being bullied by a group of the Ganelon bandits. The bandits start a fight, during which an archer named Wil lends a hand. The group then stops at a small fort where they meet Natalie, a woman looking for her husband Dorcas. More Ganelon bandits surround the fort, including Dorcas, who had joined the bandits to pay for Natalie's illness. He is convinced by Lyn to switch sides; after the bandits retreat, he decides to join the growing party. As Lyn approaches the border, two other travelers, the talkative cleric Serra and her escort, a serious mage named Erk are caught up in another fight. Both join Lyn after the bandits' defeat.

Lyn travels to Araphen, whose marquess is willing to help. Suddenly, the castle is set on fire by Lundgren's assassins and Lyn is attacked; however, Rath, a high-ranking Araphen officer and a Sacaean nomad of the Kutolah tribe, comes to her aid. The cheerful thief Matthew joins and helps them enter the barracks by unlocking doors. After the battle, Lyn meets the marquess of Araphen. However, he views Sacaeans as savages and refuses to help Lyn. Rath, who overhears his comments, leaves the marquess's service and joins Lyn.

Eliwood rescues Ninian from the Black Fang.
While passing through Khathelet, Lyn runs into a strange boy, Nils, who requests her help to get his sister Ninian back from a shady organization called the Black Fang. The two are traveling performers: a dancer and a bard, respectively. A monk named Lucius also joins, having heard Nils's plight. Lyn's forces manage to defeat the Black Fang; in the castle, they find that Ninian has already been rescued by Eliwood, the son of the marquess of Pherae. Lyn thanks him and tells him her story; Eliwood decides to help Lyn out. Ninian and Nils also start to help Lyn by using their powers, which allow them to sense approaching dangers. Ninian finds that she has lost her ring, Ninis's Grace, a keepsake from her mother. Lyn and the others are able to track the Black Fang down and reclaim Ninian's ring from them.

Lyn and her allies take down Lundgren.
Lyn continues to encounter more numerous and advanced troops on the way to Caelin. Matthew learns that Lundgren has been poisoning Hausen. Furthermore, he has also been spreading false rumors that Lyn is an impostor. Eliwood helps Lyn by convincing the other Lycian territories to stay neutral in the conflict, leaving Lundgren her only opponent. The group encounters the hearty former Caelin general Wallace, who remains loyal to Lord Hausen and believes Lyn, joining her forces.

Lyn finally reaches Castle Caelin and, after a heated battle, defeats Lundgren. She is finally able to meet Hausen, her grandfather, who is near death because of the poison. However, Lyn convinces him that they still have much they can do together, and Hausen decides to make an effort to continue living and begins to recover. When Lyn decides to stay in Caelin, Florina and Wil enter the service of House Caelin to stay with her. The rest of the characters go their separate ways, as described in their endings. The tactician Mark takes their leave to travel on their own for a time. Lyn’s tale ends here.