'Vikings' season 4 spoilers: Will Aslaug's sons avenge her death?

The situation in Kattegat gets more chaotic after Lagertha (Katheryn Winnick) finally gets her revenge against Queen Aslaug (Alyssa Sutherland) in "Vikings" season 4.

In the previous episode titled "In the Uncertain Hour Before the Morning," Lagertha stormed toward Kattegat to make Aslaug pay for everything that she took away from her. But Aslaug's death seems to have awakened a different rage within her children, especially Ubbe (Jordan Patrick Smith) and Sigurd (David Lindström).

She also has two sons who have yet to find out about her fate, since her most beloved Ivar (Alex Høgh) had been imprisoned in England with his father Ragnar (Travis Fimmel) under King Ecbert (Linus Roache), and Hvitserk (Marco Ilsø) journeys with Bjorn (Alexander Ludwig) and Floki (Gustaf Skarsgård) toward the Mediterranean.

Yet based on the trailer for the upcoming episode titled "All His Angels," it seems like Aslaug's children will also lose their father under the hands of King Aelle (Ivan Kaye). It looks like the king of Kattegat will be handled in a brutal way by the king of Northumbria, yet it also looks like he and Ivar plotted for it to happen.

According to the synopsis of the upcoming episode that was released by Zap2it, "Ragnar and Ivar plot against the Saxons and reach a new level of understanding."

This could be Ragnar's last biggest battle, since his death is imminent in the second half of season 4.

Legartha also seemed to be determined to take her place as the ruler of Kattegat. Will she succeed in her plans even if Aslaug's sons are still around to avenge their mother's death?

In an interview with The Hollywood Reporter, showrunner Michael Hirst revealed that Aslaug's death will have a big implication in Lagertha's life in the upcoming episodes. "Lagertha wouldn't be Lagertha unless she did that. And by doing it of course she challenges the gods because she knows that revenge is basic to Viking society, and the sons of Aslaug will be damned to try and avenge their mother. So she makes this huge decision, but it's a decision to kill that was based on her love for Ragnar," Hirst stated.

The History Channel will air the next episode of "Vikings" season 4 on Wednesday, Dec. 28.