The Cursed Sea by Lauren DeStefano

Wilhemina Heidle, the exiled princess of Northern Arrod, the girl thought dead by her family and friends, must return home. The only way to save Loom, the cursed prince of the Southern Isles, is to revisit the castle and discover the origins of her own curse.

But home is very different from how she left it—Wil’s unstable elder brother is now king, leading a war against the Southern Isles. And the rest of her family must reckon with the truth of what happened to lead to Wil’s exile. With time running out, Wil must navigate the dangerous secrets within her family if she’s going to find the truth and save the boy she loves.

When she’s finally able to reach Pahn, nothing goes as planned, and suddenly Wil and her allies are fighting for their lives, again and again, as the Southern King is out to punish his children for all they’ve done. Traveling across cursed seas and treacherous kingdoms, Wil, Loom—and his ruthless sister Espel—have to work to make peace with their own struggles if they hope to secure the future of their kingdoms.

But when their plans lead them right back to evil marveler Pahn, and to Baren—who is more dangerous than ever—can Wil and her friends outsmart their enemies, this time, for good?