Watch Vikings season 4 premiere live online: Will King Ragnar punish Rollo for his betrayal?

Vikings season 4 is returning to History Channel for another epic adventure. After conquering the impenetrable city of Paris in the previous season, King Ragnar Lothbrok and his Norsemen will embark on another journey but this time there will be more causalities.

The show creator of the popular historical drama has teased that this will be the best season of the series with unexpected twists in the upcoming episodes.

"I think this is our best season. And yes, there are some devastating moments that were - as usual for me - quite difficult to write and to say goodbye to people. We do death very well I think in Vikings, but it's a hard road," show creator Michael Hirst told TV Guide.

The official synopsis of the premiere episode titled A Good Treason reads:

As Ragnar lies in his sick bed in Kattegat, events unfold beyond his control; Bjorn orders the arrest of Floki for Athelstan's murder; Rollo betrays his Viking supporters to strengthen his position; Kalf announces joint Earldom with Lagertha.

Click here to watch the episode via live stream online on the History Channel.

In the finale of season 3, Ragnar staged his death and during the burial rituals, his family and friends confessed their deepest, darkest secrets to his 'lifeless' body but things turned awkward when he jumped out of the coffin and attacked Paris. In the fourth series, the King of Denmark takes note of all their confessions and will make sure they bear the brunt of his fury.

However, while doing so, he will have to struggle with his kingship as his brother Rollo has his own ambitions of becoming a Norse ruler. Ragnar also knows the truth about Athelstan's death and will punish Floki for killing him. His wife Aslug, on the other hand, is aiming to rule Kattegat with the help of the wanderer.

"A lot of the new season is about how he deals with the burden and, of course, the particular focus he has on the relationship with his brother. The Vikings are going to go back to Paris, obviously, because historically speaking, if the real Vikings found a place that was great to plunder and full of possibilities and riches, they would go back year after year. But it's not in Ragnar's nature to go back to somewhere just to plunder. He's not interested in that side of things. So for him it becomes personal - the final confrontation with Rollo," Hirst told TV Guide.

A trailer released by History Channel reveals that Rollo will back stab his own people after marrying the daughter of the King of Paris, Emperor Charles. In the trailer, a Viking with an arrow pierced in his chest can be seen shouting, "Rollo, you have betrayed your own kind. Your brother is coming. Ragnar revenge us."

Vikings season 4 premieres on 18 February on History Channel.