Lennie is alone in the barn, petting a puppy that he has obviously petted a little too long and hard, and he can't make up his mind about it.
First, he covers the dead puppy up with hay. Next, he flings the dead puppy across the barn.
We're not sure he's all that concerned about the dead puppy, actually. Instead, he's worried that George might not let him tend to the rabbits of the dream farm.
Curley's wife, who sashays in, has some advice: don't feel bad because the pup was just a mutt, and mutts are aplenty in the world.
She confides in Lennie, telling him that she could have been a famous movie star, but the world conspired against her and that's why she's ended in a barn with a dum-dum and a dead dog.
Lennie does a little confiding of his own: he got into this trouble because he likes to pet soft things.
Hm, says Curley's wife. Her hair is soft.
So, Lennie pets Curley's wife's hair.
Can you guess where this is going?
He pets a little too long and hard, and breaks her neck.
Now Lennie has something new to cover with hay.
This is bad. So bad, that now George really might not let him tend the rabbits.