"Vikings" Season 4B is currently in post-production with "Mission Impossible III" John Rhys Meyers on board. In addition to that, the official plot description of the second part has been released by The History Channel.

The cast and production crew of "Vikings" are having hectic schedules for the upcoming seasons.

According to Movie News Guide, cast member Katheryn Winnick revealed that season 4B is still in post-production. On the bright side, the production for Season 5 has already begun.

Other than that, John Rhys Meyers has officially joined the cast. His character is yet to be named and no further details about it have been released.

But series creator Michael Hirst affirmed that the 39-year-old Irish actor will play a significant role in the upcoming season, Enstarz reports.

As for the official plot synopsis of the second part of "Vikings" Season 4, Vikings Wikia notes, "In the midseason premiere, Ragnar Lothbrok's (Travis Fimmel) reappearance in Kattegat (Kevin McCann) triggers a chain of events no one - except the Seer (John Kavanagh) - could have ever imagined. He unexpectedly arrives home to see what has become of his sons and to handle unfinished business in Wessex with King Ecbert (Linus Roache).

Meanwhile, Lagertha (Katheryn Winnick) plans a power play in Kattegat and Bjorn Lothbrok (Alexander Ludwig) prepares to fulfill his long-held dream to explore the Mediterranean in a sleek new boat built for him by Floki (Gustaf Skarsgård)."

"Vikings" Season 4 Episode 11 (midseason premiere) is expected to return on Nov. 30, 2016, at 9:00 p.m. first and exclusive on History Channel. The 2nd part of the series consists of 10 episodes, making it 20 all in all. The official release date of season 5 is yet to be announced.

"Vikings" is an Irish-Canadian historical drama television series written and created by Michael Hirst.