The full title of the book is Twelve Years a Slave: Narrative of Solomon Northup, a citizen of New-York, kidnapped in Washington city in 1841, and rescued in 1853, from a cotton plantation near the Red River in Louisiana, so that gives us the time period. If IMDB is to be trusted (and I think in this case it is), then Benedict is playing William Ford in Twelve Years a Slave. According to IMDB user deconstructing “Ford is Northup’s first master. He is a Baptist preacher so it’s interesting to see this man who is dedicated to God but also thinks it’s perfectly ok to own other human beings. Still, Northup describes him as being a decent master, especially compared to the others: Tibeats and Epps. Now, the engineering skills: Northup builds a loom and helps Ford earn more money by constructing rafts to deliver lumber by canal which is cheaper than delivering them by land. I think this is the engineering skills part. Ford also helps Northup at some point, but I don’t know if you want too many spoilers.”
This seems to match up with what @CindyD1000 has tweeted, as posted to http://iranu.tumblr.com/post/28163448624/some-interesting-tweets-about-filming-twelve-years (spoiler alert!). CindyD1000 tweeted that he was wearing “greyish tan breeches, white shirt, off white vest, frockish coat—beige with a little peach in it. No cravat that I saw ;(“
This sounds amazing!