For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
Our narrator Dana tells us about how she lost her arm while travelling through time between 1976 and 1815. Then she gets into the nitty gritty details of what happened when she went back in time. It turns out that she keeps going back to visit a distant ancestor of hers named Rufus Weylin. Rufus is a white slave owner and Dana is a modern black woman, so you can imagine that there is friction between their two worlds. Dana returns to her home and present time whenever she feels as though her life is in danger. The problem is that she needs to put herself into some pretty hot water before she gets this feeling, which fills almost every page of this book with danger.
Act II
Things get really complicated when Dana's husband Kevin joins her on one of her trips to pre-Civil War Maryland. But there's an upside in the fact that Kevin can pretend that Dana is his slave and thus protect her. This strategy works until Rufus Weylin's father catches Dana teaching his slaves to read and write. He whips her nearly to death and Dana travels back to 1976 without Kevin. By the time she goes back in time again, nearly five years have passed in Rufus and Kevin's time. Dana waits and works on the farm while she waits for Kevin to return. Eventually, they reunite and return to 1976. But it's not long before Dana is called back to Rufus' time.
Act III
Rufus asks Dana to help him have sex with one of his slaves named Alice. Dana thinks this situation is appalling, but she also knows that Rufus and Alice need to have children if she (Dana) is ever going to be born. She helps Rufus until the moment her ancestor Hagar is born. Then she knows she won't have to put up with Rufus' horrible behavior anymore. On her last trip back in time, she learns that Alice has killed herself after Rufus lied to her about selling her children. Rufus tries to make himself feel better by raping Dana, so she stabs and kills him. Another slave named Nigel finds the scene and burns down the house to conceal the murder. Dana learns all about it back in 1976, where she and Kevin go to Maryland to look at the site of Rufus' house.