1842, Orry Main leaves Mont Royal, the cotton plantation near Charleston (South Carolina) he's heir to, on his way to West Point for two years of officer's training. On the way he stops a runaway carriage, meets and falls in love with Madeline Fabray, who agrees to write to him. However she is moving from Atlanta with her father, Nicholas Fabray, who needs her to wed his rude neighbor, rich Resolute plantation owner Justin LaMotte. Fighting off scum trying to extort exorbitant porters wages, Orry meets fellow cadet George Hazard, son of a Pennsylvania machines manufacturer. The hazing lives up to its reputation, not in the least due to drill master Elkanah Bent. Georgian drillmaster Bent takes particular pleasure in humbling Ohio cadet Ned Fiske at sword-practice but is humiliatingly defeated by Carolinian Orry. Madeline no longer receives Orry's letters, so she become susceptible to Justin's generous courting. George and Orry decide to share their allowances with Fisk so he must not resign to run his sick dad's farm. Bent is so hell-bent on revenge that even saving his life during a demerit points-chase is cruelly 'rewarded'. Eighteen months later George introduces Orry to his Pennsylvania family, which takes to him, and their iron factory, run by dad William Hazard and eldest son Stanley. George's sister Virgilia is instantly hostile to the slave-holder, yet also attracted. Orry stops overseer Salem Jones happily whipping slave Priam, but father Tillet refuses either to sack the sadist or consider mechanizing, without which the plantation is doing badly.

To distract Orry, whose brooding about Madeline wrecks his West Point performance, George drags him to Alice Peet for laundry and 'intimate' services. After Bent arranges for Fisk to be thrown off during a hell ride on his fiery mount Satan, Bent bluffs his way out of a court-martial but the mates arrange for its president, Lieutenant Casimir De Jong, to find his 'love rival' in Alice's bed and bully him out of West Point after a promise of eternal revenge. Two years later the gang graduates. At a welcome party hosted by pa Tillet Maine, Justin scolds Madelin for openly disagreeing with separatism and arranges slave Priam to offend publicly so overseer Salem Jones is allowed to punish his insolence with branding. Orry starts a secret affair with reluctant Madeline. Bent plays his secret trump card, Ohio's US Senator Charles Edwards, being Elkanah's natural father, to get commissioned as infantry captain in president Polk's war to wrest Texas from Mexico, and sends lieutenants Orry and George on a virtual suicide reconnaissance at Churubusco. Shell-hit Orry is crippled for life, but Constance, the daughter of Colonel Patrick Flynn MD, who saved Orry from worse, becomes George's true love. After pa William Hazard's death, George resigns and joins the firm under Stanley's directorship. Madelin helps Priam run away, Justin flogs all slaves as possible accomplices. Even Orry leaves his recluse room to join the manhunt and meets Madeline again.

1848, Orry plucks run-away slave Priam from the train Madelin suggested to flee on, George uses their friendship to let him escape. Three weeks later, Orry is best man when George weds Constance in Lehigh Station, Pennsylvania. His mother decides to give George equal share in Hazard Iron as his elder brother, Stanley, to his wife's fury. Virgilia tricks Orry into attending one of her blatant abolitionist meetings with the family, where she attracts Congressman Sam Greene's romantic attentions. Scolded by Justin for failing to give him an heir, Madeline refuses to divorce him for Orry. After an explosion due to Stanley's stinging, George is given the power of purse. After Orry's father Tillet Main dies, he fires Salem Jones. Orry permits lawyer-politician James Huntoon to court his equally ambitious sister Ashton. He scolds orphaned cousin Charles for getting dragged into a fistfight with Salem Jones's gang, but seconds and trains him for a duel with Whitney Smith whose fiancée cheated with him, winning respect and Orry's support to prepare for West Point. During the Mains' summer visit at the Hazard estate, Charles befriends fellow future cadet Billy, who is seduced by Ashton. George and Orry plan a joint-venture - a slave-free cotton mill in South Carolina, despite the political animosity. Madeline catches Justin with a slave, gets a whiplash and is afterwards comforted by Orry.

In 1854, the Hazards pay a visit to Mont Royal. Billy loses his interest in Ashton when he sees her in the cotton barn with another man and soon turns his interest to the demure Brett. Virgilia is on her best behavior, as she has promised, until she meets James Hontoon's coachman Grady and forms an instant attraction to him. After spending the night together, she helps him run away to the North which leads to a confrontation with Huntoon. Orry feels he has little choice but to ask the Hazards to leave. Virgilia and Grady are soon living together as husband and wife but that doesn't sit well with even some of the most ardent supporters of abolition. In 1856, Billy and Charles graduate from West Point with Billy assigned to the Engineering Corps in Washington and Charles assigned to the 3rd Cavalry under the command of Robert E. Lee. Billy proposes to Brett but Orry will not allow him to court her given the current situation. Ashton continues to lie her way through society and turns to Madeline when she gets into trouble. Meanwhile, Madeline's father is on his death bed and shocks her by revealing a hidden family secret.

Having locked Madeline in her room and nearly starving her to death, Justin convinces the doctor that her condition is self-inflicted. The doctor prescribes his own tonic and a daily dose of laudanum which, despite its addictive qualities, will serve to calm her nerves. Madeline is soon a very different woman: submissive and with few words to say, she has little memory of her love affair with Orry and their decision to run off together. Orry and Brett travel to Philadelphia where he wants to give his good friend George Hazard his share of the profits from their cotton mill. Unfortunately, Virgilia is also visiting leading to a confrontation with Orry over slavery. Orry and Brett leave and it will be some time before before he and George see one another. On the train trip home, they are stopped by a group led by abolitionist John Brown. Ashton, now married to James Hontoon, spends a good deal of her time in bed with lovers while her political activist husband is away promoting secession. That movement is gaining ground and war is seen as inevitable should Abraham Lincoln win the forthcoming elections.

With Abe Lincoln's election as President, secessionist feelings are running high. George Hazard pays a surprise visit to Orry at Mont Royal to apologize for what his fanatical sister said on his last visit. They resolve their differences and Orry finally gives his permission for Brett to marry Billy Hazard. Ashton is still out for revenge against Billy and arranges for him to be attacked on the street by thugs, though it turns out they're not very successful. She then turns to Forbes Lamotte to get the deed done. Billy and Brett's wedding seems to be just the right day to get the job done. Madeline overhears the plot and rushes to tell Orry who tells her she will stay at Mont Royal and never return to Justin. Elkanah Bent plots to run any blockade the North may try to impose on Southern ports. Orry travels to Pennsylvania to repay George his investment in the cotton mill and realizes the full extent of the hatred that now exists. On April 12, 1861, Confederate forces attack Fort Sumter and war is declared. George and Orry say farewell, not knowing what the future may hold for their families or their friendship.