Despite previous failed invasions, the nation of Helman allies with demons and successfully captures Leazas Castle, compelling Princess Lia to seek help from the adventurer Rance. To confront this new threat, Rance must gather three sacred royal treasures and revive the legendary magic sword Chaos. However, having previously sold some of these treasures for money, he embarks on a quest to retrieve them, which involves rescuing a girl named Laura from a monster called Liss. During his journey, Rance encounters fellow adventurers and faces various challenges that test his abilities and resolve. He joins forces with Maria, leader of the Leazas Liberation Army, to rescue citizens and mount a resistance against the invaders. Meanwhile, internal strife within Helman complicates the conflict, as Commander Patton grapples with political interference and suppressed reinforcements. As battles rage and alliances shift, Rance and his companions strive to reclaim Leazas and overcome the demonic forces.