"Descendants" actress Dianne Doan joins the cast of "Vikings" Season 4 to play the character of Yidu. Cast member Katheryn Winnick has also revealed via her Instagram account that the season 4 production is already a wrap and season 5 is already underway even though the renewal has not been confirmed yet. Plus, the official plot synopsis for episode 1 has been released by History Channel ahead of its return on air next month.

"Descendants" alum Dianne Doan officially joins the cast of "Vikings" Season 4. According to Movie News Guide, Doan is set to portray the role of Yidu, a unique Chinese woman who will have a big role in the upcoming installment. Doan's character will debut in the premiere episode. The Canadian actress TV series credits include Disney Descendants' "School of Secrets" and "Wicked World". She also reprised characters in movies like "Set It Off".

Other than that, cast member Katheryn Winnick who portrays the character of Lagertha teased via Instagram last January 16 about the show's current status. Winnick stated that Season 5's production is already underway, although, the renewal hasn't been confirmed by the network yet. Then the filming for season 4 has wrapped last year, Christian Post reports.

As for the official plot of Season 4's episode 1, Geeks of Doom notes, "Ragnar seized victory from defeat but still returns to Kattegat dangerously ill. Thoughts of his death galvanize the forces who seek to succeed him as king, including his wife Queen Aslaug and his oldest son, Bjorn.

Meanwhile, Lagertha continues power struggles with her former 2nd in command, Kalf; Rollo betrays his Vikings heritage by remaining in Frankia and Floki is seized for his brutal actions to the Christian Priest Athelstan." 

"Vikings" Season 4 Episode 1 is entitled as "A Good Treason". The series is scheduled to premiere on Thursday, February 18, 2016 at 10:00 p.m. exclusively on History Channel. "Vikings" is an Irish-Canadian drama TV series written and created by Michael Hirst.