Slim gave Lennie a puppy, which he is tending in the barn. When Curley's wife comes in, they start talking. Lennie touches her hair without realizing it because he enjoys soft things. He panics and breaks her neck when she tells him to stop doing it.
Climax
Now George will definitely not let me tend the rabbits.
Falling Action
Go back and hide in the bush by the river and wait for George