The following version of this book was used to create the guide: Chambers, Essie. Swift River. Simon & Schuster, 2024.

Essie Chambers's novel Swift River is set in 1980s New England and written from the first-person point of view. Over the course of the novel, the narrative alternates between the past and present and between chapters written from the protagonist Diamond Newberry's perspective and chapters written from Diamond's relatives' perspectives, which are presented in the epistolary form. For the sake of clarity, the following summary employs a linear mode of exploration and uses the present tense.

It is the summer of 1980 in Swift River. Eight-year-old Diamond Newberry's parents have been tense, anxious, and upset for months. After Robert Newberry, or Pop, loses his job at the mill, the family struggles to support themselves. Meanwhile, cop cars start to circle the family's house. As the only Black man in town, Pop feels alienated, afraid, and alone. He begs Diamond's mother Annabelle Newberry, or Ma, to leave Swift River and move to Georgia where his family lives. Ma has lived in Swift River her whole life and feels reluctant to abandon her home. However, she does agree to take an abbreviated road trip south in an attempt to reconnect with Pop's relatives. On the way, their plans are derailed when Pop gets arrested for punching a man at an amusement park. Just ten days after the family returns, Pop disappears. Shortly thereafter, the family finds his sneakers and wallet on the riverbank.

Seven years later, Diamond and Ma are still living in Swift River in the house where Diamond grew up. Pop still has not been declared dead. Swift River townspeople constantly insist that they have seen Pop around the area. Ma is desperate to get Pop's death certificate because she wants his life insurance and hopes to give the money to Diamond as her inheritance. However, even Ma's lawyer questions the veracity of Pop's death.

Meanwhile, 16-year-old Diamond signs up for driver's ed classes unbeknownst to Ma. She knows that Ma does not want her to drive, but Diamond is desperate for some sense of freedom. At driver's ed, she meets a girl named Shelly with whom she begins spending time. While everyone else in Swift River has belittled, ridiculed, and rejected Diamond for being Black and heavy, Shelly does not. The new friends start to spend all of their time together and bond over their similarly difficult home lives. One day, Shelly tells Diamond she is going to move to Florida when she gets her license, and she invites Diamond to come. They make plans for their departure throughout the remainder of the summer.

In the meantime, Diamond has been writing to her estranged second cousin in Georgia, Auntie Lena. Lena got in touch after she started sorting through her late mother Sweetie's old belongings. She and Diamond establish a regular correspondence. In these letters, Lena tries to explain why she and Pop stopped communicating years prior. and she tells Diamond about her town's history and the history of her family. Diamond learns about Swift River's racist past and begins to understand how this history has dictated her town's culture in the present. Lena's letters also help her get to know her Black family for the first time in her life. In Lena's final letter, she tells Diamond that she has inherited a patch of land in Canada from her great-uncle and great-aunt. She invites Diamond to visit the land together.

Diamond and Ma get Pop's death certificate. Afterward, Diamond tells Ma everything about her license, her letters with Lena, and the land. Ma agrees to let her go on the trip to Canada with Lena. While there, Diamond imagines Ma watching her in the water when she goes for a swim.