Act I. Scene 1.
Police sirens whine in the distance and searchlights probe the night sky as George and Lennie take refuge in a field. After a wait of a few moments, with George continually silencing Lennie, their pursuers seem to have passed. George gets to his feet and turns angrily on the still-huddled Lennie, accusing him of being nothing but trouble. Lennie denies this, saying he didn't mean any harm, he just wanted to touch the girl's dress, because it looked so soft. When she screamed, Lennie got so scared, he couldn't think, and wouldn't turn her loose.
George continues to grumble about the trouble Lennie causes him and how simply he could live if he were all alone. Why should he stay, when he can't keep Lennie out of trouble? Lennie pouts, "Just give me the word and I'll strike out alone," but George patiently assures his companion of his promise to Lennie's aunt and insists he stay with him.
Noticing that Lennie is hiding something, George demands that he hand it over. It is a dead mouse. George tosses it away, wondering aloud why Lennie wanted a dead mouse. Lennie confesses that it was something he could pet, something small and soft that belonged to him. He didn't mean to kill the mouse, but it tried to run away and Lennie grabbed it too tightly.
George then promises that when they get their farm he will buy Lennie some pets, maybe even some rabbits. Lennie's face brightens and he promises to be good. He begs George to retell the story of their dream farm. As George describes the clover fields and the birds, Lennie grows beside himself with delight. Suddenly the sound of the police siren intrudes on their happiness, but gradually fades away. Lennie quickly falls asleep, while George muses on their dream and how close it seems to be.
Scene 2.
The next evening in the bunk¬house, the young ranch owner Curley impatiently paces the floor, disgusted that the new ranch hands have not shown up yet. Candy, a grizzled old man with only a stump at the end of one arm says perhaps they got the time confused—Curley should give them till nightfall to arrive. Just then Curley's wife enters the bunkhouse and languidly stands in the doorway. She tells Curley she wants to go out that night. Startled to see her in the bunkhouse, Curley says he has no time to see her now. She ignores him and declares she wants to have some fun for a change. She's tired of being cooped up on the ranch with no one to talk to.
Finally she turns sweet and coquettish, cajoling him to go to the picture show. As Curley brusquely pushes her away, she explodes, demanding attention, which she'll get from him or wherever she can. Curley orders her out of the bunkhouse. Sullen but defiant, she goes to the door, turns, and bitterly declares "to think I could have been in movies, and I had to marry you."
Curley leaves and soon after, George and Lennie appear at the door. Old Candy welcomes them and warns them to keep away from the mean and feisty Curley. Soon the ranch hands are heard, singing as they return from supper. Candy introduces the two new men.
Slim, one of the ranch hands, announces his dog has just had puppies, and anyone who wants one should say so. Lennie excitedly tugs on George's sleeve, saying "I want one!"
The noise fades away, as Curley's wife reappears at the door, looking for her husband. The men try to ignore her, reminding her that Curley doesn't want her in the bunkhouse. Seeing the new men, she looks at Lennie flirtatiously, and George is alarmed. Soon she leaves, and before long the men are joking about the matter.
Carlson suddenly raises his head and sniffs the air, asking Candy if he's got his mangy old dog inside. Defensively, Candy admits he has. Slim urges the old man to get rid of the dog, who's nearly blind, almost deaf—he can take one of his new pups. The rest of the hands agree, and Slim says Carlson could shoot the dog for him. No one comes to Candy's defense, and finally he submits. Apologetically, Carlson leaves with the dog.
The lonely strains of a song are heard as the ballad singer returns to the bunkhouse. Finally the shot rings out, breaking the tension. Carlson returns and the room is silent with the reproach of the men. Lennie begs George for a pup, promising to be gentle with it.
Act II.
Late in the afternoon, several days later, George and Slim are playing a game of checkers. While George half-heartedly plays, he intently reads a newspaper. Suddenly, something in the paper arrests George's attention, and he reads with growing excitement. Realizing that he's reading the want ads, Slim remarks that every ranch hand he's ever known has had George's dream of settling down, but none of them has ever made it come true—ranch hands die alone, with empty dreams.
George refuses to settle for such a stingy life, saying there's got to be more to life than that. He wants something to show for his long years of sweat. He calls out to Lennie, who comes in, stroking his new puppy. George reads the ad describing a small farm with a garden, lily pond, alfalfa field and beautiful trees. It sounds like their place!
Candy has awakened from a nap and hears their excited talk and asks to go in with them to buy the farm. George does some quick figuring and declares that they just might swing the deal. Excitedly they imagine their life together on their farm. After some time, Curley's wife enters, claiming to be looking for her husband again. As she eyes Lennie suggestively, George orders her to leave, calling her a tramp.
Hearing Curley and Slim outside, Candy grows even more anxious, fearing for their jobs. But she is indifferent to them and casually sits down. The argument grows more vehement and George is about to strike her when Slim enters, followed by Carlson and Curley, who suspiciously asks what's been going on.
Curley's quick temper soon brings the men to blows. Hearing Lennie's nervous giggles, he turns on him and suddenly attacks him with his riding crop. Lennie desperately tries to find shelter in the bunks. Finally, George shouts, "Get him, Lennie!" Lennie grabs Curley's hand and he screams in pain. George is forced to slap his face before Lennie finally releases his grip. Curley falls to the floor, his hand broken.
After the others leave, George gets Lennie to promise there'll be no more trouble. Candy joins Lennie in urging George to read about their farm again. George very carefully cuts out the ad. The three men become lost in thoughts about their dream.
ACT III. Scene 1.
The next day inside the barn Lennie sits in a pile of loose hay, stroking his small puppy, which lies dead. He can't understand why the puppy has died and he is angry because he's lost his pet. He climbs up to the loft and hides the puppy.
Curley's wife enters the barn, carrying a cheap suitcase. As she sits down to change shoes, she is startled at a sound and sees Lennie above. She announces that she's leaving and going straight to Hollywood, where in a year, she claims, she will be a star. While Lennie dreams of their farm, she takes a doll out of her suitcase and talks to it, sharing her dream of a new life with the doll.
Lennie promises her not to tell anyone where she's gone or that he's even seen her, because otherwise, he says, George wouldn't let him have any rabbits. He explains how he likes soft things he can pet and she daintily runs her hand over her hair and remarks on how soft it feels to her when she's brushing it. Innocently, she takes his hand and puts it on her hair. His face brightens as he feels its softness.
Lennie continues to stroke her hair, and she suddenly becomes annoyed. But he is oblivious to her protests, completely absorbed in his own pleasure. She grows alarmed and begins to twist violently to free herself. Lennie is suddenly bewildered and distressed and can only hold on more tightly to her hair. Panic stricken, Curley's wife screams and Lennie clamps his huge hand over her mouth. He pleads with her not to yell, and shakes her violently. Her neck suddenly snaps and her struggling abruptly stops. When she doesn’t answer him, he releases her and she slides to the floor. Alarmed, Lennie grabs up handfuls of hay, frantically attempting to cover her body. He crouches down and realizes he has done something bad and had better hide. After a few steps he sees her doll, gently picks it up and places it beside her. Taking a handful of hay from her body, he sprinkles it tenderly over the doll. Very quietly, he leaves the barn, and the only sound is that of the horseshoe game outside.
Soon Candy comes into the barn looking for Lennie and he sees Curley’s wife. He calls out for George. George and Slim appear together and quickly realize what has happened. Slim declares that George must get to Lennie first to protect him from Curley. George looks at him imploringly. He can’t let anybody hurt Lenni –“If Lennie’s got to die,” says George, “he’s going to die happy.” In a daze, George takes Carlson’s pistol and leaves the barn.
Scene 2.
It’s near dark in the field. Lennie enters trembling and huddles close to the ground. He realizes he is in real trouble and hopes George won’t give up on him. George arrives soon, out of breath, and Lennie waits for him to “give him hell.” They hear voices off in the distance and Lennie becomes alarmed. George reassures him, saying no one is after him, that those men he hears are out chasing a runaway colt.
George asks Lennie to look out across the river and promises to tell about their little farm, to describe it so well that Lennie will almost see it. He takes the pistol from his belt and stands behind Lennie, but as he raises it his hand begins to shake, and he drops the pistol on the ground.
Very tenderly he resumes talking about how good and peaceful life will be on the farm. He tells Lennie to look again across the river; the windmill and the beautiful trees are over there.
Suddenly Lennie sits up and points, stretching his arm as if reaching for the dream, exclaiming “I see it, George! I see it!” George raises the pistol and fires. Lennie staggers and, holding on to George, slowly falls to the ground, his eyes still full of his vision. George hurls the pistol away and very deliberately takes the want ad out of his wallet and puts it in Lennie’s hand.
The ranch hands converge on George and Lennie, while George sits by Lennie’s body, almost as if unaware of them. Curley and Carlson shrug and walk off. Slim remains by his side and the ballad singer slowly leaves playing his lonely lament.