Full spoilers for this episode.
Ragnar secretly recruits men for his voyage west, asking them to trust his ship and his navigation against Earl Haraldson's orders. Lagertha wants to share the expedition, but Ragnar insists that she remain with the children and protect their home. Their argument becomes a physical fight before Bjorn interrupts. Rollo joins the crew, and Floki prepares the boat for the crossing, while news of the forbidden gathering reaches the Earl.
Haraldson answers the threat at home with violence. He tests a follower's loyalty through an offer involving Siggy, then has the man killed, and punishes the blacksmith who helped equip Ragnar's vessel. At sea, the crew faces a storm and growing doubt about whether land lies ahead. Floki treats the thunder as a sign of divine approval, while Ragnar uses ravens to search for a shore beyond the fog.
The ship reaches Lindisfarne, where the monks are unprepared for armed raiders. Ragnar's men enter the monastery, seize its treasure and kill many of the people sheltering there. Athelstan survives because Ragnar discovers that he can speak their language and decides he is worth keeping alive. Rollo questions that decision, but Ragnar takes the monk captive with other survivors. The episode ends with the raiders departing and Athelstan carried away from his destroyed community.