There was this bunch of characters who were more-or-less happy. They all got along okay but somehow, something was not quite right.
One day, certain events transpired which had the effect of bringing that something not-quite right to the fore—everyone sort-of knew this day would come; it was only a matter of time. And now, the something not-quite right was no longer something not-quite right; it was something definitely wrong!
This forced everyone in the bunch to act and to move in new directions. The situation also highlighted the different strengths of the various characters in the bunch while exposing their weaknesses. This had the effect of making them doubt their chances of any resolution while simultaneously boosting their commitment to one.
As a result of the actions taken by the characters (along with a couple of random, previously-unforeseen events) they eventually solved the problem and now the something not-quite-right was finally resolved in a very satisfying way, along with some unanticipated benefits.
However, one thing was sure. All involved knew that things would never be the same again.
Unbeknownst to the characters in the story, something of the original something not-quite right somehow managed to survive either in its original form or as a result of its effect on one or more of the characters, thus leaving open the possibility of a follow-up story(!)