It's Christmas time in the Wessex, but King Aelle looks like he's not into a festive mood. Could his reappearance in the latest episode of History Channel's hit historical drama TV series "Vikings" season 4 mean that the end of King Ragnar is drawing nigh?

As seen in the latest preview clip for episode 4 titled "Yol," the King of Northumbria is not quite happy with the current political situation of the land. With a steely gaze, he declared that he "would kill Ragnar Lothbrok."

There could be many reasons for King Aelle's interest in bringing down the mighty king of the North and those are expected to be revealed in the upcoming segment. However, there are speculations that this Christian monarch might be the very person who will be responsible for the Viking's demise. In fact, some historical accounts indicated that King Aelle has subdued the pagan king and had him thrown him into a pit of snakes.

It was previously reported that Season 4 may be the end of Ragnar's reign and fans should expect the tale to be carried out by his equally mighty sons.

"I always anticipated continuing with Ragnar's sons because many of them became as famous, if not more famous, than he was," series creator Michael Hirst told Radio Times on March last year."There was the rather remarkably named Ivar the Boneless and Ragnar's elder son [Bjorn] who sailed around the Mediterranean, and then they went to Iceland and Greenland."

In another development, the video also offers some exhilarating glimpse of Bjorn getting attacked by a man. It looks like this foe is a formidable one as Ragnar's eldest fights for his life. Rollo, meanwhile, pledges his full allegiance to Emperor Charles.

"I am prepared to defend the people of Paris to the death," he declared. His wife, Princess Gisla, however, appears to be in shock from what she has heard.

"Vikings" season 4 episode 4 "Yol" premieres this Thursday, Mar. 10 at 10 p.m. on History Channel.