The Summer's Tempest

The doctors tried to explain my mother's condition as some form of early-onset dementia.
They believe that her condition will only get worse. That she'll forget her own name, how to walk, how to talk, how to eat.
She's already started forgetting memories from years ago. She's forgotten holidays, birthdays, and other big events.
The doctors say this is only the beginning. That eventually... she'll forget me. She'll forget herself. Until there is nothing left of her but the empty shell of who she once was.
But I won't allow that to happen.
Because I know the truth.
I know what, rather, who is the cause of it.
I made a vow to find him and make him fix it.
And after doing so...
He is going to pay with his life.