Nothing good can happen when revenge is at the heart.
Six years have passed since an incident that had left her almost mentally scarred. Though the bruises had faded and everything else from that night was gone, she still held on to the anger that she felt because of that night. So when she had the opportunity six years later to cause a reunion with the same people that had hurt her in so many ways she jumped on the opportunity. It was just to let them all know in her own way that she had enough information on all of them to blackmail them if they continued with the way that they treated other people as if they were nothing.
However, the people that were there, the people that had hurt her beforehand, had other ideas of how this reunion was going to go. Each person there had their own motive for being there, and none of them were all that good. Plans had been made and now they were going to be executed along with the children of the families that were also there alongside them.
At the end of the day nothing was solved by the slight revenge except for the fact that the lake of memories could hold no more evil after it was released back to nature itself. The mystery of everything that happened was nothing more than a bunch of people's greed and the necessity to control every aspect of their lives and their children's to the point they ended their grandchildren.