The council’s preference for her tractable cousin is Princess Arianna’s biggest worry until her most trusted companion, Markmaster Tashda, kidnaps her to rekindle the centuries-long war with the neighboring kingdom, Centoren. In a fight for her liberty and the preservation of her homeland, Arianna is willing to sacrifice almost anything, but she can't escape an elite squadron of Centoreinian soldiers on her own.

A backwoods Mage and a stuttering stable boy, however, are the last champions she would have asked for. Bay is an Innate Mage who can escape neither the impulse to heal the ravaged borderlands nor the haunting absence of the master who taught him more Magic than anyone else seems to know. Even worse is Shiro, a slave illegally owned by the same inn harboring Tashda’s men. Horrified at the thought of slavery in her kingdom, Arianna swears to stop the unlawful trade if she can ever get home, and promises Shiro will never suffer chains again.

Then one of Tashda’s men catches up to them, and the glittering shield that bursts from Shiro’s hand shocks even him with the impossible: the slave is a Markmaster.

Bay departs to lead Tashda astray and Shiro, unable to explain how he got a Mark, refuses to accept his power. Arianna hopes that returning to the castle will solve their problems, but when Shiro is captured protecting her from slave-traders, she faces a choice: break her promise to Shiro and rush home to prepare her kingdom for war, or risk her life to free the Markmaster-slave who gave up everything to save her.