Here are a few suggestions (some spoilers):
Sleep of Ages, Dungeon #69
A group of adventurers must awaken a lost order of knights/paladins to fight an ancient evil. The adventure could easily be modified into a single-session dungeon crawl.
The Forgotten Man, Dungeon #75
The group must defeat an anti-paladin returning from the dead. (This would require a bit of modification, but the paladin's goddess could put the group in the "right place at the right time.")