Trama

The Viking army sets out and Paris goes into lockdown as the army prepares the defense.

The vikings launch their attack on Paris. Lagertha and Kalf lead the attack on the bridge and the main gate. After their attempt to knock down the gates with a battering ram is unsuccessful, they manage to pull them down - but are not prepared for what they find on the other side. Floki leads the attack on the wall but the city's defenses are formidable. As it becomes clear the battle is lost, Floki cannot understand why the gods have deserted him. In Kattegat, Porunn leaves her child with Auslag and goes off into the wilderness.—garykmcd

As soon as Floki has finished his siege apparatus, the Vikings start their double attack on Paris, where count Odo commands the defenders, whose courage is boosted by St.Denis's legendary 'oriflamme' relic. Ragnar's party mans the battering rams, incurring great losses to break down a city gate, only to be caught is a deadly long alley, from which they are beaten back. Bjorn and Rollo lead the storming of the walls from boats, but are also beaten, Bjorn even badly wounded. 'Emperor' Charles reappears to preside over the victory celebrations, while Ragnar confides in the late Athelstan he has a secret agenda, possibly hinting at pagan zealot Floki's utter failure. 'Usurper' Kalf, having fought side by side with Lagertha, gets her to become lovers, without burying her ambitious grudge.—KGF Vissers

Floki commands the attack on the wall to Paris with Ragnar, Rollo and Bjorn while Laagertha, Kalf and Erlendur lead the attack on the front gate. However both groups are defeated by the Christians when Princess Gisla restores the moral of her army and the Northmen survivors have to retreat. Floki questions his gods why they have been defeated and Ragnar and Bjorn are badly injured.—Claudio Carvalho, Rio de Janeiro, Brazil

Floki is convinced that the Vikings will win, as he has made a worthy sacrifice to his Gods. Ragnar continues to cling on to the Christian cross around his neck, that belonged to Athelstan.

The Vikings attack Paris. Lagertha, Kalf, and Erlendur lead an attack on the city gate; meanwhile, Floki, Ragnar, Bjorn, and Rollo try to breach the walls from boats on the river. Gisla watches from the windows of the castle and understand the strategy of the Vikings.

Lagertha unleashes the ram on the city gates. The ram itself is protected by a metal cage, that is impregnable to enemy arrows. The city gate itself is the mouth of a bridge that connects to the city on the other side of the river. After repeated blows from the ram, the city gates do not falter. Kalf and Erlendur bring in tools to puncture the gates.

The floating towers reach the ramparts but take heavy losses from the archers shooting crossbows from the ramparts. Floki convinces the Vikings that the Gods are with them and asks them to climb the towers without fear of death. The Vikings manage to get on top of the ladders of the towers and cross over to the ramparts. Victory seemed imminent.

Princess Gisla manages to restore faith in the Frank troops by revealing the Oriflamme, the holy banner of their patron, Saint Denis. The soldiers are infused with a patriotic fervor to defend the city and throw off the Vikings who had climbed over to the ramparts. The Vikings continue to send men up the towers, but they keep getting shot down. Floki is horrified to see the dead bodies of the Vikings piling up. This is when scalding hot oil is poured over the towers and are set on fire, burning the Vikings alive. Bjorn and Rollo climb up the towers themselves and Ragnar goes to save Bjorn. Gisla sees Rollo fighting on top of the ramparts. Ragnar kills many Parisian soldiers but is thrown off the walls as he is distracted looking over at Bjorn. Ragnar finds Bjorn at the bottom as well, heavily injured.

At the gates, Kalf manages to pierce the gates with huge arrows. The plan is to attach ropes at the end of the arrows to horses who will pull and bring the gate down. However, the archers manage to inflict heavy losses on the Vikings by shooting down anyone who gets close to the horses and tries to attach the ropes to them. After a lot of effort and losing many men, the gates give way. The Vikings see no Paris soldiers on the bridge and rush to the other side. Kalf senses a trap and pulls Lagertha back. As the Vikings get to the other side of the bridge, they are attacked by lances and arrows fired by a mechanized contraption. The Vikings lose many soldiers and are forced to retreat.

Eventually, the defense holds, repelling the Vikings with the use of oil, fire, and crossbows.

While the Franks celebrate their victory, at the Viking camp the warriors have to deal with their wounded, including a badly wounded Bjorn, and Ragnar who has been thrown down from the walls.

Floki is consumed by his guilt, having trusted in the good omens of their gods. Floki believes that he killed Athelstan for the greater good. Helga, disgusted by his selfishness, leaves him. Kalf tells Lagertha that he desires her and wants to be with her. Lagertha agrees to stay with him, if he accepts that she will never forgive him for taking away her Earldom, and vows to kill him one day.

Porunn leaves Kattegat and leaves her baby with Aslaug.