The Skjöldunga saga was used by Snorri Sturluson as a source when he told the story of Aðils (Eadgils) and Yrsa, in his Ynglinga saga, a part of the Heimskringla. What remains of the Skjöldunga saga is a Latin summary by Arngrímur Jónsson, and so the two versions are basically the same, the main difference being that Arngrímur's version is more terse.
Snorri relates that Aðils betook himself to pillage the Saxons, whose king was Geirþjófr and queen Alof the Great. The king and consort were not at home, and so Aðils and his men plundered their residence at ease driving cattle and captives down to the ships. One of the captives was a remarkably beautiful girl named Yrsa, and Snorri writes that everyone was soon impressed with the well-mannered, pretty and intelligent girl. Most impressed was Aðils who made her his queen.
Some years later, Helgi (Halga), who ruled in Lejre, attacked Sweden and captured Yrsa. He raped Yrsa, his own daughter, and took her back to Lejre, where she bore him the son Hrólfr. When the boy was three years of age, Yrsa's mother, queen Alof of Saxony, came to visit her and told her that her husband Helgi was her own father. Horrified, Yrsa returned to Aðils, leaving her son behind, and stayed in Sweden for the rest of her life. When Hrólfr was eight years old, Helgi died during a war expedition and Hrólf was proclaimed king.
Snorri finishes his account by briefly mentioning that the Skjöldunga saga contained an extensive account of how Hrólf came to Uppsala and sowed gold on the Fyrisvellir.
Read more about this topic: Hrodulf