A few weeks after Tom arrives on Legree’s plantation, Cassy shows up to pick cotton one day. When she sees Tom being kind to Lucy and putting cotton in Lucy’s bag, she puts cotton into Tom’s bag to help him out.
Cassy warns Tom not to be too kind or he’ll get it.
When Tom is beaten up, Cassy is the one who brings him water and tries to clean up his wounds.
Cassy reveals her back-story to Tom: she had been bought by a man who kept her as a wife, though he never married her. They had children together but, eventually, he fell in love with another woman and sold Cassy.
Separated from her children, she was sold to another man who used her. When she gave birth to another baby, she committed infanticide – she realized it was no kindness to let the child live. Finally, she ended up at Legree’s house, again a prostitute.
Cassy gets Legree drunk and asks Tom to kill him so they can all be free. When he refuses, she says she’ll do it herself. But Tom talks her out of it by agreeing to help her escape.
Cassy prepares the household and Legree for her escape with Emmeline. She puts the neck of a bottle in a hole in the garret so it sounds like moaning and screaming. She spreads stories about ghosts in the attic. When everybody is good and scared, she makes her escape with Emmeline. They hole up in the attic for a few days until everybody has stopped looking for them, then they escape.
Cassy and Emmeline meet George Shelby on the boat north. Cassy confesses her story to him.
When George Harris’s sister tells George Shelby her story, Cassy discovers that Eliza is her long-lost daughter.
Cassy and George Harris’s sister, Madame de Thoux, go to Canada, where they are reunited with their families.