Princesses Mare and Denna are finally together, but with Denna's gift of forbidden and dangerous fire magic, Mare knows settling down together will be difficult. Now, Denna must travel to the secret kingdom of Zumorda, where she can train with her fire without fear of persecution. Mare goes along with her in secret, disguised as an ambassador. When they arrive in Zumorda, though, the two princesses learn there has been an attack on a border town in Mynaria. Mare must make an alliance with the Zumordan queen to save her homeland, but the queen is only interested in Denna's powerful magic. Denna may have to choose between her fire and Mare.
