The Doctor and Sarah arrive in Renaissance Italy unaware that they have brought a deadly alien energy force with them.
Quest roles:
Terry Walsh(Guard (uncredited)), Robert James(High Priest), Norman Jones(Hieronymous), Pat Gorman(Soldier), Tim Pigott-Smith(Marco), Brian Ellis(Brother), Antony Carrick(Captain Rossini), Gareth Armstrong(Giuliano), Jon Laurimore(Count Federico), Cy Town(Dalek Operator)