The movie 12 Years a Slave presents slavery as the foundation for racism in that it depicts a free African-American man sold into slavery simply because of his race and shows the results that arise from such an act. Let's look at this in more detail.

The movie is based off of Solomon Northup's memoir Twelve Years a Slave, a book that describes Northup's capture and sale into slavery, the horrors he experiences as a slave in Louisiana, and his eventual rescue and return to his family. According to the story, racism is at the center of Northrup's experiences. Even though he was born free, his race makes him vulnerable, and he is conned into going with Brown and Hamilton, who drug him and take him to the slave trader Burch. He is sent to New Orleans where he is labeled as a runaway slave and sold.

As the movie progresses, we watch as Northrup continually declares his freedom and works to attain it again, opposed at every step by the white people around him, or if not actually opposed, at least not assisted because they are afraid of the consequences.

A Canadian worker named Samuel Bass finally agrees to send Northrup's letter north even with the risks involved, and Northrup's acquaintances finally come to rescue him and take him home.

While the movie identifies slavery as the foundation for racism, it does not actually prove this claim, and viewers should be aware that there is a much more complex story behind racism and slavery than the movie presents.