What is the first part of the movie The Butterfly Effect? Don't understand!

When a boy was a child, he always had transient amnesia, and many very bad things happened, such as a woman and a man being photographed by a woman's abnormal father and a woman's brother killing a man's dog. They killed a woman and her child because of the detonator. The grown-up man found that he could go back to the past by reading diaries or watching videos, so he went back to the past, hoping to stop those bad things from happening. But it always screws things up. The man went to divination and learned that he was a soulless man and should not have been born, and that his mother had miscarried many times before. The man finally chose to go back to the time when his mother was pregnant with him and ended his life with the umbilical cord around his neck. His three playmates all got a happy life.