In 1841, Solomon Northup, portrayed by Chiwetel Ejiofor, is a free African American man living in Saratoga Springs, New York. He is a skilled carpenter and talented fiddle player, enjoying life with his beloved wife and two children. However, everything changes when he is deceived by two men, who offer him a seemingly promising two-week job as a musician. After being drugged, Solomon awakens to find himself in chains, on the brink of being sold into slavery.
Transported to New Orleans, Solomon is stripped of his identity and renamed "Platt," the name of a runaway slave from Georgia. He faces brutal treatment from those who have enslaved him, being beaten regularly. Eventually, he is bought by the plantation owner William Ford, played by Benedict Cumberbatch, a relatively kind master. Solomon uses his skills to create a waterway that allows for the efficient transportation of logs, earning the gratitude of Ford, who gifts him a violin.
However, life on the plantation takes a darker turn as Carpenter John Tibeats, portrayed by Paul Dano, harbors resentment towards Solomon and begins to verbally abuse him. The conflict escalates as Tibeats launches a physical attack, leading to an attempt to lynch Solomon. In desperation, Ford is forced to sell Northup to Edwin Epps, a plantation owner played by Michael Fassbender, whose cruel treatment is justified in his mind by a misinterpretation of the Bible. Epps forces his slaves to pick an unreasonable amount of cotton, or face harsh punishments.
One of the slaves, Patsey, a character performed by Lupita Nyong'o, becomes Epps' particular obsession, as she is capable of picking an astounding 500 pounds of cotton each day. Epps sexually assaults her, while his wife, played by Sarah Paulson, is consumed by jealousy, further subjecting Patsey to humiliation and violence. In a moment of despair, Patsey pleads with Solomon to end her suffering, but he cannot bring himself to do so.
After a devastating cotton worm blight hits the plantation, Epps wrongly blames the newer slaves for the disaster and sends them away, temporarily leasing them to another plantation. During this time, Solomon gains favor with the neighboring plantation’s owner, who recognizes his musical talent. After returning to Epps, Solomon tries to utilize a coin gifted to him to pay a man, Garret Dillahunt’s character, to communicate with his friends back in New York. Although the man accepts the money, he betrays Solomon. In a heartbreaking moment, Solomon is forced to burn the letter, representing the last shred of hope for his freedom.
As time progresses, Solomon starts to work alongside a Canadian laborer named Bass, played by Brad Pitt. Bass openly criticizes Epps for his treatment of the slaves, which only angers Epps further. Meanwhile, one harrowing day, Epps discovers Patsey is missing and harshly punishes her upon her return. Under duress, he compels Solomon to whip Patsey, an act that deeply traumatizes him.
In a turning point, Solomon bravely confides in Bass about his abduction and pleads for his help to send a letter to Saratoga Springs. Bass, risking his life, agrees to assist him. Eventually, a local sheriff arrives with a man from Solomon’s past, confirming his identity and intent to free him. Despite Epps' furious protests and Patsey’s devastation, Solomon is liberated after twelve grueling years of bondage.
Reunited with his family, Solomon steps into his home where he is welcomed by a heartwarming sight of his loved ones, including his daughter and grandson. The film closes with an epilogue detailing the challenges Solomon faced in seeking justice for his enslavement, as well as the lingering mysteries surrounding his later life and death.
