Kill All Immortals II (Kill All Immortals II #1)

The Asvalds were once a powerful billionaire Viking family with a source of secret immortality, until the family's only daughter, Frey Asvald, led her brothers in a principled rebellion to overthrow their barbaric father and end their eternal powers. But when an ancient and supernatural adversary threatens to destroy their precarious empire and kill them one by one, they must band together as a family, survive another deadly war - and dare to test their new mortality.