S1·E20 To Reign in Hell

Catherine receives an unexpected visitor on her balcony: Paracelsus's minion Erlik, who captures her in a plot to lure Vincent to the lower parts of 'The World Below' and kill him so that Paracelsus can overthrow Father and take over the tunnels. Despite knowing what Paracelsus would do, Vincent goes to rescue her with the help of Pascal, Winslow, and Jamie.