The Queen Mound in Bloomington, MN

Book 4 in The Norsewomen Series. Ninth-century Norway. Raider Bride is headed home to Tromøy, where Ragnhild hopes to gain Åsa's aid in takng her birthright. But they must sail through perilous waters where enemies lie in wait, and Ragnhild carries a secret that could ruin her plans.
On Tromøy, an ancient evil awakes and a forgotten foe gains strength, threatening to destroy those Åsa loves.