Ms. Skloot tells the story of Mrs. Lacks’s life, from those tobacco fields in small-town Clover, Va., to the “colored” ward of Johns Hopkins Hospital in Baltimore in the 1950s, where she was treated for her cancer, and where her cells were harvested. She follows the members of Mrs. Lacks’s family to East Baltimore, where many of them live today, still struggling with her complicated legacy. As one of Mrs. Lacks’s sons says: “She’s the most important person in the world, and her family living in poverty. If our mother so important to science, why can’t we get health insurance?”

“The Immortal Life of Henrietta Lacks” is packed with memorable characters, from quirky if brilliant early researchers to Nobel Prize-winning Nazi sympathizers to long-haired Rolling Stone reporters in the 1970s to a con artist known as Sir Lord Keenan Kester Cofield. (Just when you think things can’t get weirder, Judge Joseph Wapner  the “People’s Court” television judge  makes a cameo.)

Image Rebecca Skloot Credit... Manda Townsend

Ms. Skloot is a memorable character herself. She never intrudes on the narrative, but she takes us along with her on her reporting, as she moves around the country in her battered, muffler-free black Honda. Her most complicated job is to get Mrs. Lacks’s family, who are tired of white people trying to pry information from them, to speak with her. She does eventually win them over. And Mrs. Lacks’s daughter Deborah is dead-on when she says to Ms. Skloot: “Get ready, girl. You got no idea what you gettin’ yourself into.”

Ms. Skloot writes with particular sensitivity and grace about the history of race and medicine in America. Black oral history, she points out, is full of stories about “night doctors,” men who could pluck black patients off the streets to experiment on their bodies. There was some truth behind those tales.

The author traces events like the infamous Tuskegee syphilis study, in which poor and uneducated black men with syphilis were recruited and then allowed to die terrible and entirely preventable deaths, while doctors lied to them and kept life-saving penicillin from them. Ms. Skloot makes it abundantly clear why, when Henrietta Lacks’s family learned that her cells were still living, the images that ran through their minds were straight out of science-fiction horror movies.

Mrs. Lacks had another daughter, Elsie, who was deaf and mute and possibly retarded. Elsie was shipped off at a young age to Crownsville State Hospital in Maryland, formerly known as the Hospital for the Negro Insane, and died there at 15. Perhaps the most devastating moment in this book comes when Ms. Skloot, along with Deborah, finds a grim photograph of Elsie in the hospital’s records and uncovers some of the horrors of what life there must have been like.