The book begins with Kelly Kelleher in a car that is plunging into mucky, swampy, "black water."
We learn the events that led up to the accident in flashbacks as she is drowning: Kelly Kelleher attends a fourth of July party hosted by her friend Buffy St. John and her (Buffy's) boyfriend/lover, Ray Annick. She is planning to Stay with Buffy and Ray at their home for the entire weekend. Buffy is the "more worldly" of the two young women; the irony in this is that it is completely out of character for Kelly to get herself into such a situation. Ray has invited "The Senator" about whom Kelly wrote her graduate thesis. He immediately is interested in her sexually; he pays attention solely to her as the party drags on, and they discuss their common political beliefs. He follows her to the beach where he kisses her, and then invites her to come to his hotel with him on the ferry. As she packs her bags, Buffy tries to convince her not to go or to go later but Kelly thinks that this is a once-in-a-lifetime chance and goes with him, despite the fact that he has been drinking and that she is not entirely sure that she is "ready" for any sort of relationship.
The Senator is drunk and takes the "old" Ferry Road instead of the "new" one; he is driving recklessly and drives directly through a guardrail into a marsh. We find later that, had he made the turn, the car probably would have fallen into the water a short distance down the road at an old bridge. The car sinks passenger side down.
At this point, The Senator uses Kelly's body to jettison himself upwards,out of the driver's side door. She tries to hold on to him to pull herself free; he kicks her, leaving his shoe in her hand. Kelly, badly injured and delerious, continually imagines that he will come back to "save" her, and also that he has gone for help. She repeatedly imagines seeing him outside of the car, or that she feels the car shaking as he tries to get her out (this alludes to the version of the Chappaquiddick incident told by Ted Kennedy ). She trusts The Senator until the very end of her life, certain that he will save her; it is possible that, because of this, she misses out on highly important lucid moments in which she could possibly save herself.
In reality, the senator has stumbled to an outdoor phone booth, carefully staying out of sight of passing cars, to call Ray Annick. He Tells Annick that Kelly became emotional and pushed the wheel because she was drunk, thus causing the accident, and that she is already dead.
Meanwhile, Kelly is following an ever-shrinking bubble of air to the top of the car as is fills with water. She becomes more panicked and delerious, and imagines that she is rescued and sent to the hospital where the "black water" is pumped from her stomach; this parallels an episode from college in which a suitemate tried to kill herself and had to have her stomach pumped. Kelly gets her imagery of the experience from the description of the other girl. The reader also learns about Kelly's own bout with suicidal thought and depression, triggered by the end of a relationship; Ironically, she has decided that she wants her life, that she wants to live, and this was part of the reason she decided to leave the party with The Senator in the first place.
She also repeatedly imagines her parents, and how she will explain to them that she is a "good girl" and argues that The Senator and his wife are separated, his children grown, and that their affair is causing no harm.
She remembers an article she wrote arguing against the death penalty in which she details the more gruesome and torturous aspects of different methods of execution; this underscores the cruelty and horror of her death.
As she grows closer and closer to death, her hallucinations become more vivid until she is imagining her parents, very old, watching her being pulled from the water in horror. She imagines herself as a child reaching up to be carried.
The book ends with a line that is repeated throughout the book: "As the black water filled her lungs, and she died."
It was also a finalist for the National Book Critics Circle Award in 1992.