The Secret Service S01E08 - Errand of Mercy

Suffering from heatstroke, Unwin rests at his vicarage. A newspaper article about an epidemic in Africa triggers a surreal dream in which he and Matthew are assigned to transport medicines to Bishopsville in an airborne Gabriel. Abducted by native tribesmen, Unwin must save himself and his accomplice from ritual sacrifice using his gobbledegook.