Forget Me Not follows the lives of a small group of childhood friends with a dark secret. As children they played a nasty prank on another girl their age because they thought she was a little weird, but they had no idea that this child was so wrapped up in fantasy that she actually willed something horrible to happen. What was once dormant for years, waiting, was awakened when the group returns to the spot where they used to have so much fun, and the area where the prank that they have all forgotten was played. Someone didn't forget though, and she has been waiting all this time to seek her revenge.
As they delve deep into their old game, a young girl their age suddenly pops up and asks if she can join in, explaining that she knows the graveyard very well and would be an asset to the game. Soon after it is agreed that she can play and they split off to hide from the seeker. It doesn't take long for teenagers to be teenagers and everyone is taken out of play pretty quickly. Sandy, comes across the new girl standing on a high ledge and the girl asks if she remembers her. When Sandy concedes that she does not, the girl tells her that she will and is gone.
It doesn't take long before the group begins to experience terrible horrors and are one by one targeted. In order to save her friends and ultimately herself, Sandy must remember what it is that they did so long ago to wrong this girl, and then she must figure out how to right it before it is too late. Sandy has her work cut out for her however, because the vengeful spirit is moving quickly, so much so that all of Sandy's friends, and even her own brother start to think that she has possibly lost her mind. It is just one memory she has to drudge up though, and if she doesn't get it soon there will be no-one left to protect.
As the clock races faster than anyone could possibly imagine, Sandy races to remember the group's misdeeds, what her role in it all was, and how to stop the horror before it grows out of control. With every member of the group that is picked off however, there become more complications and more spirits to deal with and before long Sandy finds herself in a terrible stand off with her past that will end in her demise if she doesn't figure out the truth in time.
There are two possible ways that this horror coaster can end check both out.