In 1841, Solomon Northup is a free African-American man working as a violinist, living with his wife and two children in Saratoga Springs, New York. Two white men, Brown and Hamilton, offer him short-term employment as a musician if he will travel with them to Washington, D.C. However, once they arrive, the duo drug Northup and conspire to deliver him to a slave pen. Northup is later shipped to New Orleans along with others who have been detained against their will. A slave trader named Freeman gives Northup the identity of "Platt", a runaway slave from Georgia, and sells him and another slave Eliza to plantation owner William Ford. Due to tension between Northup and another plantation worker, Ford sells him to another slave owner named Edwin Epps. In the process, Northup attempts to explain that he is actually a free man, but to no avail.
Some time later, an outbreak of cotton worm befalls Epps' plantation. Unable to work his fields, Epps leases his slaves to a neighboring plantation for the season. While there, Northup gains the favor of the plantation's owner, Judge Turner, who allows him to play the fiddle at a neighbor's wedding anniversary celebration, and to keep his earnings. When Northup returns to Epps, he attempts to use the money to pay a white field hand and former overseer, Armsby, to mail a letter to his friends in New York state. Armsby agrees to deliver the letter, and accepts Northup's saved money in return, but later betrays him to Epps. Northup is narrowly able to convince Epps that Armsby is lying and avoids punishment.
Northup begins working on the construction of a gazebo with a Canadian laborer named Samuel Bass. Bass is unsettled by the brutal way that Epps treats his slaves and expresses his opposition to slavery, earning Epps's enmity. Patsy sneaks off to Mistress Shaw's house to get some soap to clean herself. Epps calls her a liar and ties her to post to prepare her for a whipping. Epps hands the whip to Northup and forces him to whip Patsy. Northup reluctantly begins to whip her but Epps rips the whip out of Northup's hands and unleashes a brutal whipping on Patsy. Her back is shredded and her flesh is torn apart. Later Northup confides his kidnapping to Bass. Once again, Northup asks for help in getting a letter to Saratoga Springs. Bass, risking his life, agrees to send it. One day, Northup is called over by the local sheriff, who arrives in a carriage with another man. The sheriff asks Northup a series of questions to confirm his answers match the facts of his life in New York. Northup recognizes the sheriff's companion as Mr. Parker, a shopkeeper he knew in Saratoga. Parker has come to free him, and the two embrace, though an enraged Epps furiously protests the circumstances and tries to prevent him from leaving.
After being enslaved for 12 years, Northup is restored to freedom and returned to his family. As he walks into his home, he sees his wife with their son and daughter and her husband, who present him with his grandson and namesake, Solomon Northup Staunton. The film's epilogue displays a series of graphics recounting Northup's unsuccessful suits against Brown, Hamilton and Burch, the 1853 publication of Northup's slave narrative memoir, Twelve Years a Slave, his role in the abolitionist movement, and the mystery surrounding details of his death and burial.
Output: How many slave owner was Northup sold to?