Books in the Nineworlds series

Kendra the evil Valkyrie sorceress has stolen treasures from the gods including the belt of strength worn by Thunor and will use them to gain alliance with the fierce giants of Jötunheim.So now the children must face a perilous world of tall mountains, deep forests and icy wastes in an attempt to foil their enemy's plans.The land and weather though is not the greatest peril they must overcome for the Frost Giants of Jötunheim are a foe more fearsome than any they have faced before.