One of the most mysterious secret societies of all time is the focus of a new scripted series coming to History. “Knightfall,” a drama series about the Knights Templar, is set to premiere Dec. 6.

The series begins after the fall of the city of Acre, the group’s last stronghold in the Holy Land, where the Holy Grail is lost, History said in today’s announcement.

“Knightfall” stars Tom Cullen (“Downton Abbey,” “Gunpowder”), Padraic Delaney (“The Wind That Shakes the Barley,” “The Tudors”) and Simon Merrells (“Spartacus,” “Dominion”).

Please click here to read all the details and see a 2-minute trailer for the series.