Skloot describes a photo of Henrietta Lacks that she keeps on her wall. (It's the one on the cover of the book.)
She introduces us to Henrietta's story: she was the unidentified patient whose cancerous cells were taken and used to create HeLa cells, the first immortal cell line.
Skloot gives us an idea of the scope of HeLa cell production: there are trillions of her cells growing in laboratories all around the world, which are used for all kinds of scientific research.
She tells us that she first learned about Henrietta Lacks in a community college bio class. The teacher doesn't have any details about Henrietta's life and Skloot gets curious.
During college, Skloot begins collecting information on Henrietta's story, which wasn't much. She becomes interested in the Lacks' family story, since they seem to have been left out of the loop: they didn't know much about the HeLa cells or how they were being used.
Skloot decides that she wants to tell the family's story, and it sends her on a 10-year journey to earn the family's trust and uncover long buried information.
She also becomes involved in the life of the family, bonding especially with Henrietta's daughter Deborah, who really needed to have her mother's story told properly.
Because Skloot and Deborah are totally different, Skloot finds her beliefs and assumptions challenged during their time together.
She explains that the resulting book tells the story of the HeLa cells, but also of Henrietta's family and her own journey with Deborah.