Sky original drama Britannia is back for a third season. Set once again in ancient Britain in the 1st century AD and featuring an ensemble cast of clashing Celtic tribes, Roman invaders, and drugged-up Druids.Britannia Series Three will see the introduction of a brand new central (and terrifying ) character, played by Sophie Okonedo (Ratched). The Death on the Nile actress plays Hemple, the wife of General Aulus (David Morrissey), who arrives in Britannia to find out why her husband has failed with Lokka's mission to capture the chosen one, Cait – and she is set to shake things up.