Another pack of ideas. Use them as you wish and do not forget to send feedback in comments!
Blizzard
This story hook is a great starting point for horror/survival themed session: players' characters get lost during a snowstorm. They can see nothing but white, and the only thing they can hear is the moaning of the wind. Suddenly, they find an old, strangely looking cloak, and a moment later members of a gruesome cult start to attack them screaming something about "the secret artefact" and "the ceremony". Sessions where the visibility is limited by snow storm or fog are very easy to manage, since a GM can treat the whole scenario as a classical dungeon: places with something important for the story are like chambers, rambling in the mist is like a passage or corridor between two rooms, while the fog is "walls".
The Conqueror
This one is not so universal, for it requires specific political conditions, however, I have found it most interesting and thus decided to post it anyway. The story takes place somewhere on the border of a war zone: one country invades another and starts to push forward into their territory. The main general of the invading nation is some kind of legend - he managed to earn a nickname - the Conqueror (you can give him the first name fitting to your campaign). Thus far there is not much space for your players, is it? The problem is that the next province to conquer is the undiscovered lonesome marshland. The Conqueror and his contingent, drunk with the series of successful battles, have disappeared when they entered the land. The player characters are hired to follow their trace and find them.
