The Silver Order was a holy society of paladins who protected the valley of Barovia from evil for centuries. The group’s legendary founder and first leader, Lord Argynvost, had the fortress Argynvost Keep constructed as the center of life for the Order and one of the last bastions of resistance against evil.
Although they proved a surprisingly stalwart foe, they were eventually defeated by the overwhelming power of Strahd's forces. During a final great battle, even the mighty Argynvost was slain.
The Keep lays in ruins but not abandoned. The Revenant's of the order still haunt the grounds under their current leader Sir Vladimir Horngaard.