Vikings season 4
Ivar the Boneless seeks revenge from Lagertha History Channel

It seems the political scenario at Kattegat is taking a drastic turn after Ragnar Lothbrok's execution. Ivar the Boneless is now seeking revenge from Lagertha, who killed Aslaug after promising her safe passage.

Click here to watch episode 17 via live stream online.

In the upcoming episode, the son of Aslaug will try to find allies in his plan to kill his stepmother. Show creator Michael Hirst teases that the mother Bjorn will have a tough time ahead as Ivar is preparing for a war against her.

"Lagertha's chosen a very dangerous path. She didn't need to kill Aslaug but by doing so she's made herself a target of revenge," he told Monster Sand Critic. "Some of the sons are obliged to try and kill her. All I will say is to watch this space because she is now in an extremely vulnerable place," he added.

However, he also warned that it may not be easy to defeat or kill Lagertha considering her solid experiment in war and politics. "She's Lagertha, she's extraordinary and for the first time the History Channel has got a great female audience now, mainly I would say because of Lagertha, what she's done, what she represents, her strength and things, and she won't easily be overthrown."

The official synopsis for episode 17 titled The Great Army reads: The Viking army begins to gather in Kattegat; Lagertha must remain vigilant in the absence of her son, Bjorn.

Vikings airs every Wednesday at 9/8c on History Channel.