Princess of the Wild Swans — Diane Zahler

Princess Meriel's brothers have been cursed. A terrible enchantment--cast by their conniving new stepmother--has transformed the handsome princes into swans. They now swim forlornly on a beautiful heart-shaped lake that lies just beyond the castle walls.

Meriel will do whatever it takes to rescue her beloved brothers. But she must act quickly. If Heart Lake freezes, her brothers will be forced to fly south or perish.
With help from her newfound friends Riona and Liam--a pretty half-witch and her clever brother--Meriel vows to finish a seemingly impossible task. If she completes it, her brothers may be saved.

But if she fails . . . all will be lost.