The Rise of Runes and Shields

Witchcraft need not be evil.
Twins Freyja and Bjorn live in a time when Viking magic, called the Seidr, is deemed witchcraft and forbidden. When their home is attacked by men sent from the tyrannical local earl, who accuses their mother of a murder she did not commit, the twins are forced to flee into the night and onto an adventure to not only prove their mother's innocence but also set to rights the ills created by the misuse of the Seidr.
Along the way, they both make new friends, reunite with lost allies, visit hidden worlds, and learn the true ways of the Seidr, until they find themselves caught in the middle of the never ending war of the Fire and Frost Giants. Bjorn must learn the ways of magic and Freyja the life of the shield maidens if they are to survive.