The Curse of Faeriewell is an adventure for a level 5 group that you can easily drop into a campaign or play as a standalone one-shot. It will last between 3 and 4 hours.
It is setting agnostic, but best at home in a Fantasy world. I ran this a few times and it's been very well received.
BONUS: In the appendix of this adventure you will find a table to roll on... [click here for more]