Ragnar Lothbrok, a farmer and warrior, desires to explore new lands to the west, defying his Earl, Haraldson. Ragnar secretly builds a ship and embarks on a raid to England with his wife Lagertha and friend Rollo. They plunder a monastery, taking a monk named Athelstan captive.

The core conflict is Ragnar's ambition versus Earl Haraldson's control. Haraldson retaliates by killing those who aided Ragnar, but Ragnar eventually confronts and kills Earl Haraldson in battle, becoming the new Earl. Ragnar then negotiates with English lords, leading to Rollo's baptism into Christianity as part of a deal. The season ends with a plague devastating Kattegat, the deaths of Ragnar's children, and Ragnar's affair with Princess Aslaug resulting in her pregnancy.

Season 1 of Vikings covers episodes 1-9. Here's everything that happened:

Season 1, Episode 1: Rites of Passage - Ragnar Lothbrok, a farmer and warrior, dreams of exploring lands to the west, defying his Earl, Haraldson. After a battle, Ragnar has visions of Odin and Valkyries. He secretly commissions a new longship from Floki. Back home, Ragnar's wife, Lagertha, defends herself and kills two would-be rapists. The episode concludes with Ragnar, Rollo, and Floki embarking on an unauthorized raid to the west, challenging Earl Haraldson's authority and setting a course for future conflict.

Season 1, Episode 2: Wrath of the Northmen - Ragnar defies Earl Haraldson by secretly sailing west with a crew, landing at the Lindisfarne monastery. They plunder the monastery and take monks as slaves, including Athelstan, whom Ragnar spares. Back home, Earl Haraldson has the blacksmith who forged Ragnar's anchor killed to suppress knowledge of the voyage. The episode concludes with the Vikings discovering land after a perilous sea journey.

Season 1, Episode 3: Dispossessed - Returning to Kattegat, Ragnar's plunder is confiscated by Earl Haraldson, who allows each man only one item. Ragnar chooses the monk Athelstan as his slave, much to everyone's surprise. Later, Ragnar secures permission for another raid on England, and Earl Haraldson cruelly murders a young boy, burying him with the stolen treasure. The episode concludes with Ragnar, Lagertha, and Athelstan preparing for the next voyage.

Season 1, Episode 4: Trial - Ragnar faces a trial for the murder of Knut. Lagertha intervenes, claiming she killed Knut to prevent him from raping her, but Earl Haraldson remains unconvinced. Rollo's testimony ultimately saves Ragnar, leading to Knut's death being officially attributed to self-defense. The episode concludes with Ragnar realizing his conflict with Haraldson is inevitable, setting the stage for future confrontation.

Season 1, Episode 5: Raid - Earl Haraldson, seeking to eliminate Ragnar, launches a brutal attack on Ragnar's farm, terrorizing Lagertha and the children. Ragnar, though wounded, manages to escape with his family via a hidden tunnel. He then confronts the Earl, leading to a fierce battle where Ragnar ultimately defeats and kills Earl Haraldson, securing his own position as the new Earl.

Season 1, Episode 6: Burial of the Dead - Ragnar, still recovering from injuries, challenges Earl Haraldson to single combat. Rollo, having endured torture, intervenes to save Ragnar by killing Haraldson's henchman. Earl Haraldson is slain by Ragnar, and Siggy avenges her daughter by killing Thyri's abusive husband. The episode concludes with Ragnar being declared the new Earl of Kattegat.

Season 1, Episode 7: A King's Ransom - Ragnar captures King Ælle's brother, Lord Æthelwulf, and demands a hefty ransom. Ælle agrees to pay if one Viking converts to Christianity, leading to Rollo's baptism. However, Ælle reneges on the deal and attacks, resulting in Æthelwulf's death. Ragnar ultimately receives the ransom after sending Æthelwulf's body back to Ælle.

Season 1, Episode 8: Sacrifice - During a pilgrimage to Uppsala, Ragnar grapples with the loss of his unborn son and seeks divine intervention. Athelstan, increasingly integrated into Viking culture, is unwittingly chosen as a human sacrifice to appease the gods. Ultimately, Leif volunteers to take Athelstan's place, offering himself to the gods. The episode concludes with Ragnar forming a strategic alliance with King Horik.

Season 1, Episode 9: All Change - Ragnar travels to Götaland to negotiate with Jarl Borg on behalf of King Horik, but Jarl Borg manipulates Rollo into betraying Ragnar. Meanwhile, a devastating plague sweeps through Kattegat, claiming the lives of Siggy's daughter Thyri and Ragnar's daughter Gyda. The episode concludes with Ragnar consummating his affair with Princess Aslaug, leading to her pregnancy.