History Channel has released a powerful trailer of Vikings season 4, hinting at more bloodshed and crown politics between King Ragnar Lothbrok, his ex-wife Lagertha, son Bjorn and brother Rollo. The premiere episode of season 4 of the hit drama series will air on 18 February. The series will take a break after the first 10 episodes and will return with the remaining 10 episodes later this year.

Warning: Potential spoilers ahead

The trailer of the upcoming season hints at a complex equation between the leader of the seafaring vikings of Kattegat and his brother Rollo. In the season 3 finale, the French Emperor Charles offered the latter, land, title and his daughter. In the premiere of season 4, Rollo will not only accept the offer but as shown in the trailer, he will betray his fellow vikings to gain political stability with King Charles.

In one of the promos, a dying soldier is heard shouting, "Rollo, you have betrayed your own kind. Your brother is coming," and it ends with the soldier saying, "Ragnar revenge us."

Meanwhile, Aslaug, will secretly aim at becoming the ruler of Kattegat and will seek the guidance of the Seer about the possibilities of a woman ruling the kingdom. Instead of answering the question, the Seer, however, will hint that the death of Ragnar cannot be ruled out.

The synopsis of season 4 reads as follows:

Season three culminated with the extraordinary battle in Paris, where Ragnar (Fimmel) seized victory from the jaws of 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 (Alyssa Sutherland) and his oldest son, Bjorn (Alexander Ludwig). Meanwhile, Lagertha (Katheryn Winnick) continues power struggles with her calculating, former second in command, Kalf (Ben Robson); Rollo (Clive Standen) betrays his Vikings heritage by remaining in Frankia and Floki (Gustaf Skarsgård) is seized for his brutal actions to the Christian priest Athelstan.

The upcoming season will also reveal the fate of Floki who killed Christian priest and Ragnar's friend Athelstan in the previous season.