Kill mice?

While subjected to the loneliness and mediocrity of the life they presently lead, George and Lennie's prospect of their own farm attracts yet another hopeful, Crooks, the African American stable buck. Despite their best efforts, however, the dream begins to collapse, completely falling apart when Lennie accidentally kills Curley's wife by breaking her neck after he refuses to stop petting her hair (The feel is resemblent to rabbits according to Lennie.) He said to himself, "I done a bad thing. I done another bad thing." It was foreshadowed in the beginning of the book, as in the last ranch they worked at, Lennie began to touch a woman's dress, and they were going to be lynched until George hid with Lennie, and later on escaped. After Curley's wife, who is a promiscuous woman with a wandering eye, dies in his arms, Lennie escapes to the river where the story had begun, the place where George advised him to hide should he ever get into trouble (Note the circular ending: it suggests that the workers are trapped in the cycle forever).