A treasonous plot is brewing in Kattegat.

Ragnar (Travis Fimmel) is surrounded by snakes on Vikings. The King of Norway is on his way out - physically and politically - and the warrior is well aware that threats are mounting against him. In episode 5, it appears King Finehair (Peter Franzén) and Halfdan the Black (Jasper Pääkkönen) will win another convert to their side. Floki (Gustaf Skarsgard) is none to pleased with his former BFF, and unlike during season 2, the boat builder's scheming won't work in Rangar's favor.

Watch Harald and Halfdan engender Floki's support in the following sneak peek.

Note how completely unfazed Harald is when Floki speaks of Athelstan's murder. Together, the would-be king, Floki, and Aslaug (Alyssa Sutherland) all have one this in common - utter indifference for the lives of Chirstians. When it comes down to it, however, Finehair is the one leading the charge.

"If you were to think of Ragnar like on the liberal wing of the Viking party, these people are the ultra-right," series creator Michael Hirst told IGN. "They have no conscience. They have no sensitivity to people of other religions or faiths. So they are a real threat."

Even though Ragnar knows what machinations Finehair and his brother have brewing in the background, he will have to look past the issue for the time being. AS you saw in the season 4 trailer, the future usurpers will soon sail alongside the warriors of Kattegat.

"You're in that strange halfway house of you know this person probably wants to overthrow you, but in the short-term you need him," Hirst told Zap2It. "There's a lot of fun to be had down the line."

With all that's going on up north, it's easy to forget that Ragnar will face an equally formidable threat down the Seine. Rollo (Clive Standen) proved his loyalty to Paris when he slaughtered his own troops, and now that he is in Gisla's (Morgane Polanski) good graces, who knows what traitorous acts he could perpetrate against the Norsemen as the season wears on.

Find out how Ragnar will handle Harald, Halfdan, Floki, and Rollo when Vikings airs Thursdays at 10 p.m. ET on the History Channel.

Tags: vikings television history channel