In the midst of Reconstruction, a time of terror and trouble looming in the South, "the love strain is still heard above the land's miserere." In an outdoor love scene in a pine forest, Ben and Elsie kiss, and he presents her with a "love token" - a white dove. (Silas Lynch spies on them, watching fair-skinned Elsie.) But the defeated South cannot easily forget: "bitter memories will not allow the poor bruised heart of the South to forget." In the garden, Phil approaches good-humoredly through the foliage and affectionately tries to talk to Margaret, his former lover. But she stares ahead and then at him, with a stony expression on her face - she refuses to speak to him. Her face is captured with a cameo-profile. She draws away from him and goes to another part of the garden. She sees in her imagination, in a balloon vignette as a separate shot, a medium-closeup of dead brother Wade on the battlefield.

Although Elsie and Ben are in love, they still represent opposite sides of the conflict: "Pride battles with love for the heart's conquest." They hesitate in a kiss, and then abandon themselves to each other, in a beautiful outdoor setting. They experience a combination of "love's rhapsodies and love's tears." After they return to their separate locations, Elsie is obviously in love - in the privacy of her own bedroom, she excitedly hugs and kisses the bedpost [a phallic symbol?].

Election day comes. Blacks are given the ballot and they take over the political polls, while the leading white citizens are disenfranchised. Negroes and carpetbaggers sweep the state in the election, and are elected to a largely-black legislature. Silas Lynch is elected Lieutenant Governor and becomes a fierce zealot for "black supremacy." The blacks shoot their guns into the air in the streets to orgiastically celebrate their equal rights.

Ben Cameron, the Little Colonel, relates a series of outrages that have occurred to other whites. Verdicts are rendered against whites by negro juries. The faithful Cameron family servant is punished for not voting with the Union League and the Carpetbaggers. She is tied with her arms up and whipped in the back. After the war, the chambers and galleries of the House of Representatives in the State House, Columbia, South Carolina, 1870 are shown in "an historical facsimile." The Negro party is in control of the Congressional session: there are 101 blacks against 23 whites in the session of 1871. In a lap-dissolve shot, the legislators and gallery-visitors come into view in their seated and standing positions.

In the first historic session of the legislature and during Reconstruction, blacks are luridly and angrily portrayed as mocking the ideals of the Old South. The freed negro legislators are depicted as power-crazy, shiftless, lazy, idiotic, sitting shoeless (sprawled with bare feet upon their desks) in the legislature, behaving in a disgraceful manner, and abusive toward "faithful" Negroes who prefer the good old days of subjugation. A law is passed that whites must salute negro officers in the streets. The white minority is helpless. And a bill is passed allowing for the intermarriage of blacks and whites. Political equality for blacks has mushroomed to include much more.

In an outdoor scene on a hillside overlooking a river, Ben contemplates the fate of the nation and his homeland. He is "in agony of soul over the degradation and ruin of his people." As he sits in contemplation while fearing black supremacy, he sees white youngsters donning white sheets and pretending to be ghosts to frighten a group of black children. This is an "inspiration" to him -- thus, the Klan is born:

The result. The Ku Klux Klan, the organization that saved the South from the anarchy of black rule, but not without the shedding of more blood than at Gettysburg.

Ben organizes together with other southerners to form a secret vigilante group, the Ku Klux Klan, known for their white garb and night-riding activities. The white and scarlet robed-and-hooded regalia of the KKK and their horses have two distinguishing features - a large Cross of St. Andrew embroidered on the front of the robes of both rider and horse, and an 18 inch spike in the center of the Klansman's helmet.

The KKK's main purpose is to frighten blacks and keep them in their place, to counteract "the Black Menace," and to restore order and "home rule" - thereby saving the South from powerlessness. The KKK's first visit is to terrorize a "negro disturber and barn burner." They instill fear in the two blacks, who shiver and flee in fright. Lynch's supporters score the first blood against the KKK, shooting three white-hooded Klansmen dead from their horses. This stirs up "the new rebellion of the South." Stoneman is shown the white costumes of the victims:

We shall crush the white South under the heel of the black South.

Elsie is told that Ben, her "lover belongs to this band of murderous outlaws." Because of wartime divisions and hostilities, Ben is estranged from Elsie who remains loyal to her father's efforts. "Confirmed in her suspicions, in loyalty to her father, she breaks off the engagement." Although she knows of Ben's involvement in the Klan (his white hooded costume is revealed when it falls from inside his coat), she spitefully stomps off (with steely-eyes) and distances herself, but then returns and promises to secretly keep this knowledge to herself: "But you need not fear that I will betray you."

"Over four hundred thousand Ku Klux costumes made by the women of the South and not one trust betrayed." Little Sister Flora consoles the disconsolate lover - her brother, by planting multiple kisses on his cheeks. She also hides KKK costumes in bedpillows. At the same time, in her bedroom, Elsie (in an iris-highlighted pose) stares blindly ahead past the cage holding her white dove 'love token' - and then weeps at the foot of her bed.

Against her brother's warning, Flora, the delicate young Cameron daughter, cheerfully ventures alone to the spring to fetch water in a bucket. By a fence, an emancipated former house servant/slave - the inflamed, lusty Negro "renegade" Gus (Walter Long) notices her. At the spring, Flora dips her bucket in the water as he follows her path in the forest. From his hiding place in the underbrush, he watches her sitting on a log, where she gestures and plays with a squirrel (in closeup). A closeup of his face displays an ominous look. However, he approaches (with hope) and confronts her with the news that he is now a distinguished military officer and ready for marriage:

Gus: (touching his uniform hat) You see, I'm a Captain now - and I want to marry -.

When he takes her hand as a gesture, she slaps him, jumps over a log, and runs off. He pursues her after the rejection and chases her through a sun-splattered pine-forested area (with dramatic, natural contrasts of light and shadow). In the meantime, to heighten tension, there are cross-cuts to scenes of Ben being notified of Flora's errand at the house, and his efforts to reach her in the forest (he retraces their steps through familiar settings). As he chases after her, Gus reassures Flora:

Wait, missie, I won't hurt yeh.

After a long and exciting pursuit sequence (involving all three characters: Ben, Flora, and Gus), Flora scrambles higher and higher up a rocky cliff. As Gus approaches closer toward her and gestures for her to come down, she turns and repeatedly threatens him: "Stay away or I'll jump." With arms outstretched, Flora appears to lose her balance and she falls off the cliff - seen from a long shot. [It could be interpreted that she committed suicide by jumping or leaping off the cliff to her tragic death, to avoid being raped and suffer dishonor, but it is more likely that her death is merely an accident. However, it could be interpreted that her threatened rape symbolizes the emasculation and 'rape' of whites in the South by a rampant black population suddenly emancipated - and destructive of the racial order.] At the scene of the fall, a fearful Gus is made an innocent victim - he will undoubtedly be held accountable and punished for her demise.

Looking down from the summit, Ben sees a mortally-wounded Flora at the foot of the cliff. As she lies almost lifeless in his arms, he wipes her bloody brow with the Confederate flag she has around her waist. After a few words, she collapses and dies. Vengeance is seen in his facial expression, although the intertitle advises not mourning for her:

For her who had learned the stern lesson of honor, we should not grieve that she found sweeter the opal gates of death.

He carries her body home. The entire Cameron family are stunned by the tragic turn of fate. "And none grieved more than these" - sorrowful blacks also grieve her death.

"The son's plea against his father's radical policy." (A short segment as an interlude.)

With Flora's head on a pillow, Ben is reminded of the hidden KKK costumes, and he leaves in haste, with revenge in mind. Gus hides in "white-arm" Joe's ginmill. Ben enlists townsmen to search for the accused Gus, so "that he may be given a fair trial in the dim halls of the Invisible Empire." In a dramatically-dynamic segment, one of the white men Jeff (Wallace Reid) confronts the group of blacks hiding Gus in the ginmill, and engages them in a brawling fistfight involving chairs and bare fists. As Jeff emerges outside, he is shot twice in cold blood, once by Gus at close range.

Gus flees for his life to a nearby corral. White townsmen see him and chase after him. The fugitive leaps on a horse and spurs it, with two of the townspeople in pursuit. At the same time, the film cuts to Ben with two others - they suddenly hear distant shooting and run toward the sound. The white townspeople who are still giving chase fire widely at Gus but miss. Then one of them pauses, steadies his gun, takes careful aim and fires. The bullet kills Gus's horse, causing it to collapse underneath him. Gus leaps to the ground and flees on foot. Gus is trapped in a field between Ben and his friends and the townspeople converging from behind. He is seized by the arms and collar, captured, and dragged off. The accused is summarily given a "fair trial" by the white-robed Klan, found guilty, and then lynched in an execution. [Segments of his original punishment - castration - were deleted after the film's first showings.] His body is deposited on the steps of the Lieutenant Governor's house - this is their answer to the blacks and carpetbaggers.

Silas Lynch discovers Gus' body the next morning. In retaliation, he orders negro militia reinforcements to fill the streets. The Hon. Austin Stoneman takes his "temporary departure" to avoid the consequences of the coming conflict. The Klans prepare for action - still outraged by Flora's death which is regarded as "a priceless sacrifice on the altar of an outraged civilization." Ben leads the Klansmen in vowing revenge for her sacrifice. Meanwhile, Lynch dispatches spies to hunt out whites in possession of the costume of the Ku Klux - the penalty for being a Klan member is death by execution. Silas Lynch is "happy, at last, to wreak vengeance on Cameron House." Elsie's ideals are crushed, leaving her bitter. White scalawags and black militia storm the Cameron house and seize elder Dr. Cameron for harboring Klansmen and for having KKK costumes in his possession.

Fortuitously, Dr. Cameron, with Phil and Margaret, are rescued by their two loyal black servants (known as "faithful souls"), after being paraded in chains before their former slaves. The Camerons, servants and Phil Stoneman flee from town - the former slave masters and the child of an abolitionist are now under attack by former slaves. Elsie learns that her brother Phil has slain a negro during the rescue of Dr. Cameron. In their flight, they reach the edge of town and find refuge in a little isolated cabin, their country home, occupied by two Union veterans. They are welcomed in - "the former enemies of North and South are united again in common defence [sic] of their Aryan birthright."

Meanwhile, a frightened, fair and white Elsie proceeds to the mulatto leader Silas Lynch for help - totally "ignorant of Lynch's designs on her." After Lynch attempts to force marriage upon her, Elsie threatens him with a "horsewhipping for his insolence." Lusting for power and miscegenation, his intention is to marry her, by force if necessary. He tempts her by offering to make her Queen of his "Black Empire." Klansmen are summoned on horseback (first a few upright white male riders, then a group, then a horde of white-sheeted figures) as Lynch corners a horrified Elsie while she screams in fright. "Lynch, drunk with wine and power, orders his henchmen to hurry preparations for a forced marriage."

A standing line of Klan on horseback is viewed as they are summoned, assembled and gathered for reinforcement, and to restore order. Some of them hold aloft a burning cross - as they ritually consecrate themselves to their appointed mission. They gather in full strength for the rescue in a "head-on" tracking shot. Elsie faints into Lynch's arms just as her father arrives to save her. Lynch tells him of his plan: "I want to marry a white woman." Her father congratulates Lynch by patting him on the shoulder and shaking hands - prior to learning Lynch is referring to HIS own daughter, when the audacious Lynch adds a few moments later: "The lady I want to marry is your daughter." Only then is Stoneman repulsed and furious.

At the same time, Ben leads the Klan to the rescue of white womanhood, white honor, and white glory. It is an intense, action-packed, stupendous, last-minute rescue finale, a thrilling climax - interweaving the siege on the cabin, the chaos in Piedmont, Elsie's fate at the hands of Silas Lynch, and the onrushing rescue by the Klan. During the rescue, the most famous sequence in the film, excitement is heightened by shots of the Klan alternating with shots of the endangered Elsie - the film exhibits masterful parallel editing. Along a country road, the Klansman ride to their appointed mission - to first rescue Elsie, and then to rescue the entire Cameron family along with one of the Stoneman boys. In a diagonally-angled shot, a long line of KKK riders comes into view from the distance.

In town, Elsie screams when she sees white spies disguised as blacks. She breaks a window to summon help. Outside town, the besieged cabin where the Camerons have taken refuge is attacked by black militia and carpetbaggers - the Union veterans refuse to allow Dr. Cameron to give himself up. Helpless whites, "victims of the black mobs," and some sympathizers with the KKK look on at the rioting, chaos and confusion in the streets of Piedmont.

Zealous, heroic KKK on horseback arrive in Piedmont [the Klansmen are followed with a moving-camera and/or viewed riding in a long line through the country]. They mass at the edge of town, regroup, and then open fire, driving Lynch's black militia from Piedmont after a bloody gun battle. They also arrive just at the last moment to rescue Elsie from Lynch's clutches, before she or Austin Stoneman are hurt.

They must ride to the rescue in a frenzied second climax, to save the besieged cabin from a rabble of blacks and carpetbaggers breaking down the cabin door. Two striking images are presented - a Union veteran stands with his rifle butt poised over his child's brains lest she be molested by the militia - the child's frightened face is seen in close-up in the last moments of the cabin attack. The Klan triumphs, however, and saves the cabin and disarms the blacks. White supremacy is restored back to the South as the white-robed Klan heroes ride back into town in a triumphant celebratory parade, joined by the rescued whites.

The blacks are crushed and disenfranchised in future politics. In the next election, Klan members supervise the elections with guns drawn. The aftermath also includes a post-war reunion in the film's conclusion. The two couples (in the Cameron and Stoneman families), after marriage, are brought together in a "double honeymoon" - Phil and Margaret are reconciled, contemplating a sunset through their window [a double-exposed view]. Then in another quick, poetic tableaux - Ben and Elsie sit by the sea's edge, symbolic of the peaceful rejoining of North and South after many battles and the painful Reconstruction period.

The allegorical Epilogue prophesies the coming of the "Prince of Peace."

Dare we dream of a golden day when the bestial War shall rule no more. But instead - the gentle Prince in the Hall of Brotherly Love in the City of Peace.

Symbolic images of the demonic forces of war - throngs of suffering people and piles of dead corpses - are dispersed and dissolved into a scene of angelic people seen in flowing robes. A tableau with a benevolent Christ-like figure emerges from the background, signifying the vanquishing of the God of war, and the reign of everlasting peace, unity, harmony and brotherhood throughout the world. Elsie and Ben are viewed together again - the film fades to its final subtitle:

The Birth of a Nation: Does it refer to the re-established 'united' states, or to the "birth" of the Invisible Empire - the Ku Klux Klan?