Oddny and Gunnhild meet as children in tenth century Norway, and they could not be more different: Oddny hopes for a quiet life, while Gunnhild burns for power and longs to escape her cruel mother. But after a visiting wisewoman makes an ominous prophecy that involves Oddny, her sister Signy, and Gunnhild, the three girls take a blood oath to help one another always.

When Oddny’s farm is destroyed and Signy is kidnapped by Viking raiders, Oddny is set adrift from the life she imagined—but she's determined to save her sister no matter the cost, even as she finds herself irresistibly drawn to one of the raiders who participated in the attack. And far to the north, Gunnhild, who fled her home years ago to learn the ways of a witch, is surprised to find her destiny seems to be linked with that of the formidable King Eirik, heir apparent to the ruler of all Norway.

But the bonds—both enchanted and emotional—that hold the two women together are strong, and when they find their way back to each other, these bonds will be tested in ways they never could have foreseen in this deeply moving novel of magic, history, and sworn sisterhood.