They had given Lennie a puppy and he would always go inside the barn to pet it. Curley's wife enters and she starts to have conversation with Lennie. He then begins to grab her hair because he likes soft things. But then she gets agitated, screams & tells him to stop. He panics because he is afraid George will get mad and accidentally breaks her neck trying to keep her quiet.
Lennie then remembered that George had told him if anything bad ever happens to hide near the river , so he goes and George meets him there,
George finds him before Curley does. So he begins to distract him and Lennie asked him to tell him their story of their future. So as George tells the story, he shoots Leenie in the back of the head.