During cross-examination, she reveals that her father is usually "tol'able" ("good" or "easy to get along with") except when he's drinking. Although she asserts that her father "never touched a hair o' my head in my life," he could beat her when "he's riled" - drinking. Evasively, she is uncertain whether the critical day was the first time she had ever asked him to come inside the fence. And she can't recollect "if he hit me" but then changes her mind. When Miss Mayella identifies the attacker as the defendant Tom Robinson, Atticus asks him to catch a water glass tossed at him - he does so with his right hand. Tom explains that his left arm is useless:

I can't use my left hand at all. I got it caught in a cotton gin when I was twelve years old. All my muscles were tore loose.

Mayella's testimony is disjointed, confusing, and forced, and leaves no doubt that she is lying. Cornered when Atticus asks: "Do you want to tell us what really happened?", she loses her composure. The naive, beleaguered woman grimly shouts toward the accused black man and the jury, and then runs from the witness stand to elicit sympathy:

I got somethin' to say. And then I ain't gonna say no more. He took advantage of me. An' if you fine, fancy gentlemen ain't gonna do nothin' about it, then you're just a bunch of lousy, yella, stinkin' cowards, the - the whole bunch of ya, and your fancy airs don't come to nothin'. Your Ma'am'in' and your Miss Mayellarin' - it don't come to nothin', Mr. Finch, not...no.

Tom Robinson takes the stand to testify and states that he had to pass the Ewell place going to and from the field every day. For over a year, Mayella had often invited him inside the fence to do chores, but he never charged her: "Seemed like every time I passed by yonder, she'd have some little somethin' for me to do, choppin' kindlin', and totin' water for her." On the night of the alleged beating and rape, Mayella invited Tom inside the house to fix a door that didn't need fixing - it was uncharacteristically quiet with all seven children in town getting ice cream with seven nickels she had saved to treat them ("She said it took her a slap year to save seb'm nickels..."). Uncomfortable with the next bit of testimony, Tom's nostrils flare and his forehead breaks out into a nervous sweat:

Well, I said I best be goin', I couldn't do nothin' for her, an' she said, oh, yes I could. An' I asked her what, and she said to jus' step on the chair yonder an' git that box down from on top of the chifforobe. So I done like she told me, and I was reachin' when the next thing I know she...grabbed me aroun' the legs. (A murmur erupts in the courthouse) She scared me so bad I hopped down an' turned the chair over. That was the only thing, only furniture 'sturbed in the room, Mr. Finch, I swear, when I left it....Mr. Finch, I got down off the chair, and I turned around an' she sorta jumped on me. She hugged me aroun' the waist. She reached up an' kissed me on the face. She said she'd never kissed a grown man before an' she might as well kiss me. She says for me to kiss her back. (Tom shakes his head, re-living the ordeal with his eyes half-closed) And I said, Miss Mayella, let me outta here, an' I tried to run. Mr. Ewell cussed at her from the window and said he's gonna kill her.

Although Tom unequivocally denies raping or harming Mayella Ewell in any way, Gilmer establishes that the defendant was "strong enough" to hurt the woman. The prosecutor also insinuates some ulterior motive on Tom's part: "How come you're so all-fired anxious to do that woman's chores?" Tom reveals that he performed the chores for free - and foolishly admits that he felt sorry for the white woman:

Tom: Looks like she didn't have nobody to help her. Like I said...
Gilmer: With Mr. Ewell and seven children on the place? You did all this choppin' and work out of sheer goodness, boy? Ha, ha. You're a mighty good fella, it seems. Did all that for not one penny.
Tom: Yes, sir. I felt right sorry for her. She seemed...
Gilmer: You felt sorry for her? A white woman? You felt sorry for her?

Later that day, Atticus bravely proves the innocence of his client in a final, low-keyed defense summation to the emotionless jury. He begins by stating that the case never should have been brought to trial: "The State has not produced one iota of medical evidence that the crime Tom Robinson is charged with ever took place." He asserts that the testimony of Mayella was "called into serious question" and was "flatly contradicted by the defendant."

Atticus uses the testimony about Tom's useless left hand to illustrate that the white girl Mayella ("the victim of cruel poverty and ignorance") couldn't have been struck by Tom Robinson. She was savagely struck, beaten, and raped by someone who was left-handed [Mayella was clearly injured from a beating by her father]. He vigorously and powerfully argues that Mayella lied because she broke a code that prohibits a white woman from becoming sexually attracted to a black man - an unspeakable offense:

...in an effort to get rid of her own guilt. Now I say guilt, gentlemen, because it was guilt that motivated her. She has committed no crime, she has merely broken a rigid and time-honored code of our society. A code so severe that whoever breaks it is hounded from our midst as unfit to live with. She must destroy the evidence of her offense. But what was the evidence of her offense? Tom Robinson - a human being. She must put Tom Robinson away from her. (He gestures, pushing away with his hands.) Tom Robinson was to her, a daily reminder of what she did. Now what did she do? She tempted a Negro. She was white, and she tempted a Negro. She did something that in our society is unspeakable. She kissed a black man. Not an old uncle, but a strong, young Negro man. No code mattered to her before she broke it, but it came crashing down on her afterwards.

Atticus asserts that the Ewell witnesses thought, with "cynical confidence," that they could get away with their false testimony and trusted that the jury would agree with them. His argument is convincing - Mayella failed in seducing Tom Robinson, and then falsely accused him of rape after being beaten by her father for making sexual advances toward a black man. Atticus looks into the eyes of the jury with quiet authority, patience, fair-mindedness, and a strong sense of right and wrong, arguing further that it should not be assumed that all whites tell the truth and all black people lie:

The witnesses for the State, with the exception of the Sheriff of Maycomb County, have presented themselves to you gentlemen, to this court, in the cynical confidence that their testimony would not be doubted. Confident that you gentlemen would go along with them on the assumption, the evil assumption, that all Negros lie, that all Negroes are basically immoral beings, all Negro men are not to be trusted around our women. An assumption that one associates with minds of their caliber, and which is in itself, gentlemen, a lie, which I do not need to point out to you. And so, a quiet, humble, respectable Negro, who has had the unmitigated temerity to feel sorry for a white woman, has had to put his word against two white peoples. The defendant is NOT GUILTY, but somebody in this courtroom is.

His final appeal to the jury to acquit the defendant and show moral courage is presented with dignity and eloquence:

Now gentlemen, in this country, our courts are the great levelers. In our courts, all men are created equal. I'm no idealist to believe firmly in the integrity of our courts and of our jury system. That's no ideal to me. That is a living, working reality. Now I am confident that you gentlemen will review - without passion - the evidence that you have heard, come to a decision, and restore this man to his family. In the name of God, do your duty. In the name of God, believe Tom Robinson.

Several hours later, the jury returns to the courtroom. Despite a convincing defense, the case is hopeless from the start - the accused black man is convicted by the prejudiced white jury. Atticus tells Tom as he is handcuffed and led from the court that he plans to appeal: "I'll go to see Helen first thing in the morning. I told her not to be disappointed, we'd probably lose this time." After the courtroom clears, Atticus gathers his papers and walks down the middle aisle in defeat. The blacks in the balcony stand to show dignified respect as he passes out the courtroom door. Rev. Sykes alerts Scout to stand in his honor:

Miss Jean Louise, stand up, your father's passin'.

Although Atticus' defense has caused him to suffer many injustices, his compassionate defense has won him the respect and admiration of his two motherless children and the black community.

Later that night, neighbor Maudie Atkinson commiserates with Atticus' loss and summarizes for a disappointed Jem the thankless work that his father does in a world of human irrationality: "There are some men in this world who are born to do our unpleasant jobs for us. Your father's one of them." After hearing from Sheriff Tate, Atticus explains that Tom fled from the authorities and was shot to death while supposedly trying to escape:

Tom Robinson's dead. They were taking him to Abbottsville for safekeeping. Tom broke loose and ran. The deputy called out to him to stop. Tom didn't stop. He shot at him to wound him and missed his aim. Killed him. The deputy says Tom just ran like a crazy man. The last thing I told him was not to lose heart, that we'd ask for an appeal. We had such a good chance. We had more than a good chance.

At the Robinson home where Atticus goes to deliver the bad news to the family (to Helen and Spence, Tom's father), Helen collapses when she senses that Tom is dead. A hate-filled, disgraced Bob Ewell confronts Atticus in the yard and after glaring spits into his face. With spit rolling down his cheek, Atticus defiantly steps forward, glares back, wipes the spit from his face with a handkerchief, and climbs into the car.

By the next fall, the memories of the trial have faded, as adult Jean Louise remembers in voice-over:

By October, things had settled down again. I still looked for Boo every time I went by the Radley place. This night my mind was filled with Halloween. There was to be a pageant representing our county's agricultural products. I was to be a ham. Jem said he would escort me to the school auditorium. Thus began our longest journey together.

Jem escorts Scout to the school building to attend the Saturday night pageant. Scout carries a giant ham costume that she will wear for Halloween. When it's almost ten o'clock and time to return home, Scout has to wear her ham costume because she has lost her dress and shoes: "I'll feel like a fool walking home like this." In a moving camera shot through the dark wooded area between the school and their home, the trees rustle around them. Stopping and starting, Jem repeatedly believes he hears heavy footsteps walking behind them in the eerie, Southern gothic sequence. To confront their ghost, Scout yells out an echoing retort: "I'll bet it's just old Cecil Jacobs tryin' to scare us. (Yelling) Cecil Jacobs is a big wet hen." Jem guides his sister with a hand on her costume while looking back and hearing distinct footsteps.

A shadowy form attacks Jem and hurls him to the ground. As she struggles to get out of her awkward, cumbersome ham costume, Scout is thrown down and rolls around inside the protective outfit. She hears scuffling, grunting, kicking, and pounding sounds as Jem wrestles against his attacker and shouts "Run, Scout!" He is seriously injured and rendered unconscious. When the assailant [a disgraced Bob Ewell] turns toward Scout, a second pair of hands intervene from an unseen man - they wrestle with her attacker and come to her defense. Through the view-hole of the ham, Scout watches in wide-eyed horror as the scuffling sounds of a second struggle die down and there is silence. From her point of view, she watches a pair of legs cross her path and under a street light, she sees Jem's limp body being carried home by a mysterious person. After removing her costume, Scout follows closely behind and sees her brother being carried into the Finch yard.

Atticus runs down the steps of his house and picks Scout up in his arms, asking: "What happened?" He alerts Calpurnia to get the doctor and then phones Sheriff Tate to report: "Someone's been after my children." Jem has been found unconscious, bruised, and lying on his bed inside his room. Dr. Reynolds (Hugh Sanders) diagnoses a badly-fractured arm: "...like somebody tried to wring his arm off." The Sheriff arrives with Scout's ham costume and reveals a disturbing find in the woods to a shocked Atticus:

Bob Ewell's lyin' on the ground under that tree down yonder with a kitchen knife stuck up under his ribs. He's dead, Mr. Finch....He's not gonna bother these children any more.

As Scout relates what happened, she notices a man in the corner of the bedroom behind the door - she identifies him as the one who grabbed Mr. Ewell and carried Jem home:

Why, there he is, Mr. Tate. He can tell you his name...

The Sheriff moves the bedroom door, revealing in the light a terrified, gentle man with a pale face, thin blonde hair, white skin, and dark shaded eyes - a brain-damaged, ghostly Boo Radley (Robert Duvall finally makes his crucial appearance in a non-speaking role, his first film role), who appears to have spent much of his life locked in a sun-deprived environment (a cellar?). As he returns a protective, loving look, Scout gazes at him with wonder in her eyes and then a timid smile breaks out on her face. Now a flesh and blood character who turned out to be her guardian angel, she no longer fears him as the horrible ghost of her fantasies:

Scout: Hey Boo.
Atticus: Miss Jean Louise, Mr. Arthur Radley. I believe he already knows you.

Scout goes to him, takes his hand and leads Arthur over to Jem's bed to say goodnight. Jem is asleep - his left arm in a cast. She encourages him to tenderly touch Jem: "You can pet him, Mr. Arthur. He's asleep. Couldn't if he was awake, though. He wouldn't let you. Go ahead." She leads "Boo" out to the front porch where they sit quietly on the rocking swing.

At first, Atticus believes that Jem had killed Ewell and that there must be a defense established: "It'll have to come before the County Court. Of course, it's a clear-cut case of self-defense." Sheriff Tate enlightens Atticus:

Mr. Finch, do you think Jem killed Bob Ewell? Is that what you think? Your boy never stabbed him.

They look up toward Boo and Scout who sit peacefully on the swing. Boo would have to be defended in court, but would never be able to survive the notoriety of a trial. To atone for his errors in judgment in the Robinson/Ewell case and for the death of an innocent man, the Sheriff proposes a cover-up to protect the harmless, innocent Boo from "the limelight" of public prosecution. He fabricates a story, asserting that Ewell drunkenly fell and was killed on his own knife. Ignoring the prospect of Atticus' defense of Boo, the Sheriff speculates that Atticus may not want to participate in the cover-up of the truth:

Bob Ewell fell on his knife. He killed himself. There's a black man dead for no reason, and now the man responsible for it is dead. Let the dead bury the dead this time, Mr. Finch. I never heard tell it was against the law for any citizen to do his utmost to prevent a crime from being committed, which is exactly what he did. But maybe you'll tell me it's my duty to tell the town all about it, not to hush it up...To my way of thinkin', takin' one man who's done you and this town a big service, and draggin' him, with his shy ways, into the limelight, to me, that's a sin. It's a sin, and I'm not about to have it on my head. I may not be much, Mr. Finch, but I'm still Sheriff of Maycomb County, and Bob Ewell fell on his knife.

Scout rises from the swing and walks over to her father - he puts her up at eye-level on a chair. Scout affirms Sheriff Tate's wisdom, revealing her own grown-up understanding that it would be inhumane to subject Boo to a defense trial even if it could be proven that he killed Ewell to protect them - it would be an egregious sin to "kill a mockingbird":

Scout: Mr. Tate was right.
Atticus: What do you mean?
Scout: Well, it would be sort of like shooting a mockingbird, wouldn't it? (They hug each other closely)

Boo rises and walks over to peer in Jem's window. Atticus walks over to Boo and shakes his hand in gratitude, concurring with the Sheriff's decision to hush-up the killing:

Thank you, Arthur. Thank you for my children.

The conclusion of the film is moving and melodramatic, especially with Elmer Bernstein's poignant closing score. In a backwards moving shot, Scout walks the timid Boo Radley (with his hand in hers) to the Radley gate and up their front walk. Jean Louise, in her adult voice-over, narrates the remainder of the film's dialogue:

Neighbors bring food with death, and flowers with sickness, and little things in between. Boo was our neighbor. He gave us two soap dolls, a broken watch and chain, a knife, and our lives.

Boo opens the door to his own house and goes inside. Scout lingers for a few moments on the front porch and at the front gate before slowly returning home. She views the world from a new angle - from Boo's perspective. In her awakening intelligence and perception of the nature of good and evil, and right and wrong, she senses what Atticus had earlier told her about never really understanding a person "until you consider things from his point of view...until you climb inside of his skin and walk around in it":

One time Atticus said you never really knew a man until you stood in his shoes and walked around in them. Just standin' on the Radley porch was enough. The summer that had begun so long ago had ended, and another summer had taken its place, and a fall, and Boo Radley had come out.

The film concludes with memories of her childhood: her brother, her friends, justice, and her father. The camera pulls out of the window in Jem's room, where Scout is cradled in her father's arms, to a long shot of the Finch house:

I was to think of these days many times. Of Jem and Dill and Boo Radley, and Tom Robinson - and Atticus. He would be in Jem's room all night, and he would be there when Jem waked up in the morning. [Play clips (excerpt): (short) (extended)]