"Vikings" season 4 returns with an episode that hints at a looming letdown for Ragnar.

Episode 5 teases that betrayal is soon to beset Ragnar, played by Hollywood actor Travis Fimmel.

"Betrayal is in the air at the court in Paris and Wessex," a synopsis for episode 5 reveals. This happens as Ecbert (Linus Roache) backs Kwenthrith (Amy Bailey) in Mercia, while Ragnar finds a new confidante in Yidu (Dianne Doan) with whom he will share his gravest secret.  The synopsis also reveals that Lagertha (Katheryn Winnick) and Kalf (Ben Robson) are going to have a child soon.

According to Ecumenical News, the upcoming episode features several characters playing for more power but shows very little of Ragnar.

In another trailer for the episode titled "Promise," Halfdan is shown egging on the other Vikings by telling them that they are "the masters now." It also shows Ragnar gazing at the commotion while Lagertha hammers away in a scuffle. The clip suggests that she still has what it takes to be a fighter despite her pregnancy, as she can still keep the invaders at bay while the Christian king orders a wide-ranging invasion.

The video teaser for episode 5 also reveals a budding kinship between Floki (Gustaf Skarsgard) and Queen Aslaug (Alyssa Sutherland). In the clip, Floki and his wife join some Vikings at a table. When one of the men asks Floki why his friendship with Ragnar seems to have fallen to pieces, Floki simply answers: "He killed my pet Christian." Floki and his wife then share a toast with Aslaug.

In other news, Travis Fimmel is reportedly leaving the show to focus on his Hollywood career. How his story will end in the series is now a brainteaser for many of his fans.

"Vikings" season 4 airs on History Channel on March 17.