Complex sentence: According to "Heimskringla", Halfdan's second wife, also named Ragnhild, had been kidnapped from her home by Hake, a "berserker" who encountered her father in Hadeland and killed him.
Split into simpler sentences: According to "Heimskringla", Halfdan's second wife was also named Ragnhild. She was kidnapped from her home by Hake, a "berserker" who encountered her father in Hadeland and killed him.