As Dana Franklin travels through the past, she is sent back to her own time, 1976, when her own life is in danger. 

In Octavia Butler's novel, Kindred, an African American woman named Dana, suddenly finds herself, after a feeling of nausea, not in her home in 1976, but in the pre-Civil War South. Dana saves a young white boy, Rufus Weylin, from drowning and gives him CPR. Rufus' mother believes Dana is trying to kill Rufus. A man then points a gun at Dana which causes Dana to faint. As Dana faints, she is transported back to her own time and wakes up to find herself back in 1976. Later, Dana figures out that Rufus is her ancestor and that she must keep him alive long enough for him to father Hagar, another of Dana's ancestors. Unfortunately, this means that Dana has to be complicit in Rufus raping Alice, the slave who is Dana's ancestor/Hagar's mother, or Dana will not exist.

In short, when Rufus is in danger, Dana is drawn to the past; and when Dana is in danger, she returns to 1976. The mechanism for how she is transported is not explained in the novel.