This is a simple idea which has always appealed to me, even despite the fact that I am not a huge fan of Fantasy.
A small village is being besieged by goblins. 16 years ago, a party of adventurers saved the village from another tribe of goblins, and then left.
The characters are the youths of the village, sent out to seek those heroes, so that they may help the village again.
Once they get to the nearby city, after some adventures on the road, they find the heroes, only to discover that they had fallen to various vices, and are busy wasting away.
Will the characters rehabilitate the heroes, or will they become heroes themselves?
Of course, given the timeline, it is entirely possible that some of the characters are actually children of the heroes…
When I originally came up with the idea, I was thinking of using Big Eyes, Small Mouth to run it, but if I do it now, I would rather use Legends of Anglerre.