"Vikings" season 4 will show an old Ragnar returning to lead his already grown-up sons.

The recent promo video released for the second half of "Vikings" season 4 offers a glimpse of all the major characters in the series, including Floki and Lagertha, along with the white and bearded Ragnar and his grown-up children.

History confirmed that the clip belongs to the remaining episodes of season 4, which will air this fall. This explains why the footage shows no sign yet of Jonathan Rhys Meyers, who was recently confirmed to join the cast of season 5 as a regular.

"Vikings" season 4 brings Ragnar Lothbrok back to power in Kattagat. He, together with Bjorn Ironside and Sigurd Snake-In-The-Eye, will discover that Ivar the Boneless is actually a much bigger threat than the treacherous Rollo.

The upcoming season will resume the six-year time jump, where Ragnar comes face to face with his grown up sons in Kattegat. In the season 4 midseason finale, Ragnar issued a challenge to Bjorn Ironside, Ubbe, Hvitserk, Sigurd Snake-In-The-Eye and Ivar to rule Kattegat.

As season 4 resumes this fall, Bjorn, Ubbe, Hvitserk, Sigurd and Ivar will prove that they are not the type anyone should just be messing with. Also, Ragnar will prove his worth as a ruler.

According to Michael Hirst, the events in the second half of "Vikings" season 4 will be such that fans will be grateful that Rollo did not kill Ragnar Lothbrok in the previous installment. He also teased that the continuation will also make fans "cry buckets."

History has not made any official announcement yet as to when "Vikings" season 4 will return.