Once a peerless Mechsteel pilot in his youth, Watt Sears is now nearing forty and content with his quiet life as a humble station employee in a frontier city. As a self-proclaimed old man, he spends his days showing new pilots the ropes, repeatedly turning down pleas from his boss and the local lord to return to his former role as a Steelrider, an elite monster-hunting mech pilot. This peaceful existence shatters when Anna, his long-lost daughter from a bygone romance, suddenly appears and asks for his help. Resolving to protect her, Watt is immediately thrust into a violent struggle for the throne of the kingdom of Ogdenn.

The story follows Watt as he abandons his retirement and reclaims his old post as Top Knight, not for glory, but to support Anna as she navigates a treacherous path to power. After a cataclysmic battle that ends with Anna taking her place as the young queen, Watt devotes himself to serving as her blade. The narrative then expands from a military conflict into political intrigue as the duo are summoned to the Corona Senatus, an international congress of crowns. There, Watt must face a new kind of enemy for a father suitors arriving from other nations to ask for his daughter's hand in marriage, all while a surprising reappearance from his own past threatens to complicate everything.