Respect his mind. Protect his body. Cherish his heart. These sacred vows forever bond two men with love and devotion, but in the ancient city of Arachovia, such a union comes with a price.

Matthias, the first-born son of the House of Helianth, has one path to inherit his family's power and wealth: marrying a respectable woman and fathering children to carry the bloodline. Despite his obligations, the young noble jeopardizes his family's honor to devote himself to his lover, Anton. But when Anton refuses to sacrifice his own familial duty and marries a random noblewoman, Matthias finds himself without a lover, title, or future.

Acting with little thought for his safety, Matthias condemns himself to the bloody, demanding, and often brief life of a soldier. His survival will depend on mastery of an arcane weapon, trust in the other soldiers of his unit, and a captain with a mysterious past.

Matthias soon finds a renewed sense of purpose alongside his shield-brothers, a sacred order of magic-wielding priestesses on the battlefield, and another chance to experience true love. But when the machinations of a neighboring city-state and a group of ambitious nobles threaten the peace they have fought so hard to maintain, Matthias and his companions discover their actions will either save their world or destroy it.