At the end of Uncle Tom's Cabin, Tom is sold to the evil and alcoholic Simon Legree, who owns a cotton plantation. Legree, a hardened man, has created a system that subjects enslaved workers to horrific conditions for his own gain. Legree finds it is cheaper to buy slaves, quickly work them to death, and then replace them rather than keep a group of slaves long term in decent conditions. He picks a few slaves to be overseers, tasked with keeping the others under control. The overseers are rewarded for behaving with the utmost cruelty and ruthlessness. Legree's hellish plantation is isolated so that there are no witnesses to his abuses.
Legree wants Tom, who is physically strong and has a commanding presence, to be an overseer. Tom is enslaved, but he long ago determined that while white people can own his body, nobody can own his soul. He obeys his masters, despite utterly hating being enslaved, but he will not cross moral lines to serve them.
Legree is infuriated that Tom refuses to become an overseer. He abuses Tom severely, hoping to change his mind. Tom's moral strength, however, is stronger than Legree's coercion. In the end, Legree has Tom beaten to death, but he ultimately fails to own Tom's soul.