10 years previous to the invasion of Britannia. In a barren wasteland under the hot desert sun, Aulus commands Lucius to end the life of the man being crucified.
Two years on from the initial invasion of Britannia, Amena who now Queen of the Cantii tribe and lover to Aulus, is working with Celt tribes to negotiate for their cooperation with the Roman Empire. Those who don't comply will be crushed.
Aulus continues the search for Cait in secret and her blind father, Sawyer as he sees them as a threat to his power as per the prophecy. Claudius arrives and interrupts his plans and after learning of Claudius' attempts to have him return to Rome now the Empire has control of Britannia, he takes big measures to ensure Claudius knows the threat the Druids pose.
The Druids hold a synod in an effort to learn from the gods, to understand what their next move should be to combat the Romans. Veran channels a message from his past and Willa and Quane recognise this as signs the Dead Man has woken up.
Cait continues her training with Divis so she can fulfil the prophecy, but must take a leap of a cliff as a leap of faith to complete the Trial of the Air.
- David Morrissey as Aulus Plautius
- Nikolaj Lie Kaas as Divis
- Mackenzie Crook as Veran
- Eleanor Worthington-Cox as Cait
- Annabel Scholey as Amena
- David Bradley as Quane
- Gershwyn Eustache Jnr as Vitus
- Liana Cornell as Ania
- Hugo Speer as Lucius
- Jodie McNee as Willa
- Paul Chahidi as Domitius
- Steve Pemberton as Emperor Claudius
- John Marquez as Felix
- Francis Magee as Rork
- Liran Nathan as Crucified Man
- Garry Cooper as Chieftain 1
- Andy Gathergood as Chieftain 2
- Andrew Greenough as Chieftain 3
- Trystan Gravelle as Derog
- Sion Alun Davies as Halwyn
- Andy Secombe as Tribal Elder
- Mark Flitton as Roman Soldier
- Bessie Coates as Daughter
- Christopher Hatherall as Blind Father
- David Langham as Physician
- Camilla Watson as Raven
- Caoilfhionn Dunne as Brearn
- Caolan Byrne as Arin
- Owain Gwynn as Morac