In Rome, Aulus makes a sacrifice to the cult of Lokka; back in Britannia, Aulus tries to negotiate with the Druids before he receives a visitor; Cait has a bone to pick with Veran.
Antedia escapes from cruel captivity and Cait runs from a brief encounter with Lucius at a Roman Road Building Camp; Hemple and her Acolytes are now established in Aulus's Villa.
Cait and Antedia team up on the road whilst Divis struggles to cope with a novice Druid and new arrivals in camp; Aulus visits the Underworld and Cait witnesses Antedia's vengeful nature.
Cait and Antedia stay together after running from trouble; Amena and Willa appear to set a trap for Aulus and Hemple; Veran gathers the Druids and Cait selects companions for a journey.
Cait and her team's rescue mission to free Lucius is thwarted by Aulus who gets there first; Veran seeks to destroy and mounts a devastating and unexpected attack on Aulus's Villa.
Amena and Hemple follow in Aulus's footsteps; Cait and her band find a snake trap in the form of a huge Roman Aqueduct where they plan an attack; Aulus interrogates Lucius about the spear.
Aulus takes Lucius and a few survivors to a remote fortress where he is joined by Amena and Hemple; Cait finds her way to the fort and Antedia launches an attack with a firestorm, as Divis and others arrive.
The Dead Man, Harka, meets with Hella and asks her to find someone for him; Divis tends to Cait's injuries following the Trial of Air.
In animated flashback, brothers Harka and Veran play together as young boys in a natural paradise; Harka is unhappy and ends up killed by a snake, believing Veran betrayed him.
Hella pays Aulus a visit with an offer she knows he won't be able to resist; after paying Hella in silver, Aulus gets hold of information to lead him to the Chosen One.
Divis has an awkward dream that causes tension in his relationship with Cait, in the midst of their preparations for the Trial of Water.
After deserting the Roman Army, Philo and Brutus are enjoying their freedom and deepening their knowledge of psychedelics.
As sole survivor of the druid attack on the Roman camp, a traumatized Vitus returns to the castrum with a message for Aulus from the Dead Man; Aulus rides away, leaving Vitus in charge.
Aulus returns to the castrum where Domitius confronts him; Aulus reveals to him that he serves Lokka, an omnipotent being that came before the Roman Gods; Domitius barely has time to take in this outrage before Aulus strikes.
Divis wakes up alone and is trapped under the Dead Man's spell, unable to stand up; he realizes Love was sent by Harka and is heartbroken that he has failed the prophecy.
Amena has to face Aulus again, but the previous events have changed her and she nurses in her heart a desire for vengeance.
In A.D. 43 Britannia, the Celts are a feuding group of tribes, but conflict pauses after General Aulus Platius and his Roman invaders arrive. Rogue druid Divis, on a covert mission, finds a friend in Cait, a young Celt.
While King Pellenor is confident his army can destroy the Romans, Kerra muses another approach. Cait and Divis struggle to connect. An attempted mutiny goes awry. General Aulus teams up with Cantii's enemy and seeks help from a shocking source.
Aulus returns from his visit to the Underworld; Pellenor is furious to learn of Kerra's secret visit to the Romans; Divis persuades two Romans to get him into the enemy camp; Cait reunites with Divis to provoke a change in plans.
Camped out in a deserted village, Phelan is not convinced by Ania's confidence in her prophecy; Cait and Sawyer find solace, but it is cut short when Divis' demon Pwykka tracks them down; Roman deserters contemplate the gods.
Divis tries to track down the abducted Cait; the siege of the Cantii reaches a bitter and violent end; Phelan and Ania seek answers from Druid Veran, who considers the hope that is left for them in the form of Cait.