While Ragnar must deal with the aftermath of the fatal storm, Bjorn goes to meet his uncle. Meanwhile, Lagertha returns to Kattegat.
As they near Paris, the Vikings relaunch their boats, but this time they bear interesting structures made by Floki; Aethelwulf and Alfred arrive in Rome, where honors are bestowed by Pope Leo IV, but in Wessex, relations are less than cordial between King Ecbert and a disgruntled King Aelle.moreless
Ragnar launches the attack towards Paris. Rollo is however prepared for his fellow Vikings. In Wessex, King Ecbert sets out to meet Prince Wigstan who then gives an tempting offer to the King. In Kattegatt, Harbard meets the women of the village.moreless
It's Christmas time. Ragnar spends some alone time with the new slave Yidu. Bjorn has an unexpected encounter in the forest. Ragnar come home to find his chair in the great hall occupied by another king.moreless
Both Ragnar and King Ecbert gets a visit by Athelstan. Aethelwulf comes home after a successful rescue mission. Rollo tries to learn the language in Paris which proves difficult.
Floki has escaped and the search for him is on. In Wessex the King gets some bad news about his allies. Aethelwulf is off on a rescue misson.
As a second assault on Paris is being prepared, Emperor Charles must make a difficult decision. Meanwhile, in Wessex, Judith must make her own difficult choice.
The populace of Paris is in a panic after the appearance of the Viking fleet, and Emperor Charles, at the behest of his daughter, announces he'll remain in the city.
While Rollo worries about the Seer's prophecy, the Vikings make final preparations for their raid on Paris.
Tragic circumstances greet the fleet on its return to Kattegat; Lagertha is usurped and convinces Ragnar to help her reclaim her title.
An alliance angers Floki; Princess Kwenthrith makes political moves.
As the new Viking settlement prepare for their first harvest, King Ecbert pays them a visit.
A mysterious wanderer arrives in Kattegat; Lagertha and Athelstan establish a Viking settlement.
King Ecbert proposes a deal to the Vikings in the Season 3 premiere. Later, Ragnar leads his forces into battle.
A politician in Prague is framed for murder, triggering the team's effort to take down the Kingmaker, a shifty strategist who's behind the rise of powerful politicians. Meanwhile, Liz unearths a secret that Red has been hiding.moreless
Ragnar's invading party are met with extreme violence when they march on King Ecbert's villa.
Horik and Ragnar travel to Wessex, but their true purpose is disputed. Meanwhile, Princess Aslaug's prepares to give birth.
Justice is dealt to Jarl Borg, and allies are made on both sides of the sea.
Ragnar receives an unexpected offer from King Horik and Lagertha's new husband doesn't seem overly pleased to see her. Meanwhile, Athelstan becomes King Ecbert's trusted aide.
Lagertha is once again reunited with Ragnar and Bjorn make another choice. Meanwhile, Athelstan finds it difficult to define his faith and Aslaug has to accept the consequences of her prophecies.