In the next episode of "Vikings," Ivar the Boneless (Alex Høgh Andersen) joins King Harald of Tumdrip (Peter Franzen) to take down Queen Lagertha of Kattegat.

The trailer for the upcoming installment, which is titled "The Message," was just released recently, and it shows Harald meeting with Ivar in Tumdrip's great hall. "You and your warriors will support me when I attack Kattegat," Harald says to the Boneless One as they feast at the dining table.

"There's a full moon tonight. Let us say that we will attack in two moons time," Ivar replies with resolve. It appears he will finally avenge the death of his mother Aslaug (Alyssa Sutherland). As fans will recall, she was shot in the back by Lagertha last season and took over Kattegat. Ivar swore that he would kill the Queen sooner or later.

Meanwhile, it seems that Lagertha and Ubbe (Jordan Patrick Smith) are going to form an alliance to fend off Harald and Ivar. "Ubbe, you will lead our army," she says to him. He left his brother Ivar because he thought that he was getting out of control. "Yes, against my two brothers. This is going to rip my father's legacy apart," Ubbe says in a determined tone. Lagertha then clarifies with him that the Seer told her that the battle will tear their world apart.

In the last episode, Bishop Heahmund (Jonathan Rhys Meyers) attacked the town of York, which they thought was empty. However, Ivar and the Vikings, who were hiding in the sewer, then emerged to surprise the Saxons. Most of them were killed, and Bishop Heahmund was captured by the Vikings. Ivar and his army won the bloody battle, and he was pleased with the capture of the defiant bishop.

"Vikings" season 5 episode 6 will hit the airwaves on Wednesday, Dec. 27, at 9 p.m. EST on the History channel.