In the Prologue to The Immortal Life of Henrietta Lacks, author Rebecca Skloot describes an old photograph of a pretty, fearless-looking young woman with light brown skin. It is a picture of Henrietta Lacks, who died of cervical cancer in 1951. A few months before her death, a doctor cut out a small sample of her cancer cells, which became the first and most important line of human cells ever to survive and multiply indefinitely in the laboratory environment. Her cells have helped scientists make some of the most important advances in modern medical history—but they were taken without her knowledge and without her permission.

Rebecca Skloot became interested in this story when, at the age of sixteen, she enrolled in a community college biology class to fulfill a high school science requirement. Her teacher, Donald Defler, gave a lecture about the amazing qualities of human cells. In it, he mentioned that cell reproduction was “beautiful…like a perfectly choreographed dance.” He explained that even one mistake in this dance can cause cells to reproduce uncontrollably: cancer.

During his lecture, Defler told his class that when Henrietta Lacks was diagnosed with cancer, scientists had been trying and failing to make human cells reproduce in a laboratory for decades. For some reason, Henrietta’s cells were different. They survived and reproduced indefinitely in a tissue culture, becoming a cell line scientists named HeLa. HeLa cells have now lived outside Henrietta’s body longer than they lived inside it, and they are still helping researchers learn about human cells, to develop treatments for cancer, and to study countless other diseases.

At the end of his lecture, Defler added one piece of personal information about Henrietta Lacks: “She was a black woman.” Rebecca wanted to know more, so she found Defler after class and asked whether Henrietta Lacks had known how important her cells were. Defler did not know. Neither Rebecca’s biology book nor her parents’ encyclopedia had any further information either.

When Rebecca went on to study biology in college, she found that “HeLa cells were omnipresent” in her field. She continued to seek out information about Henrietta Lacks, but no other professors mentioned her. Many college biology textbooks said that the woman who produced the cells was named Helen Lane.

Eventually Rebecca found some articles about Henrietta Lacks from the 1970s. From them, she learned that the Lacks family was not informed about HeLa until almost 25 years after Henrietta’s death, and they were shocked to find out that the cells were now being sold for profit. According to the article, the family felt “that science and the press had taken advantage of them.”

In graduate school, Rebecca studied nonfiction writing, and she decided to try telling Henrietta Lacks’s story. She spent a decade searching for information about both the cells and the woman whose body they came from. In the process, she befriended Deborah Lacks, who was convinced that her mother’s spirit wanted the story told.