A British aristocrat played by Peter Cushing is killed by the Knights who say "ni" and it's up to his son coming all the way from America to solve the case. The whole thing is extremely silly, but Donald Pleasence, the head of "The Knights of Avalon" (a society dedicated to the medieval values of live, unfortunately gone vigilante), manages to look fairly omnious in full knights armour. Quite hard to track down these days.
Review of A Dirty Knight's Work
