It's 1983 and seventeen-year-old Grace Clark has just lost her mother when she begrudgingly accompanies her estranged father to an archeological dig at Olduvai Gorge on the Serengeti plains of Tanzania. Here, seventy-year-old Mary Leakey enlists Grace to sort and pack her fifty years of work and memories.

Their interaction reminds Mary how she pursued her ambitions of becoming an archeologist in the 1930s by sneaking into lectures and working on excavations. When well-known paleoanthropologist Louis Leakey commissions her to illustrate a book, she's not at all expecting to fall in love with the older married man. Mary then follows Louis to East Africa, where she falls in love for a second time, this time with the Olduvai Gorge, where her work defines her as a great scientist and allows her to step out of Louis's shadow.

In time, Mary and Grace learn they are more alike than they thought, which eventually leads them to the secret that connects them. They also discover a mutual deep love for animals, and when Lisa, an injured cheetah, appears at camp, Mary and Grace work together to save her. On the morning Grace is due to leave, the girl—and the cheetah—are nowhere to be found, and it becomes a race against time to rescue Grace before the African bush claims her.

From the acclaimed author of The Invincible Miss Cust and The Woman at Wheel comes an adventurous, dual timeline tale that explores the consequences of our choices, wisdom that comes with retrospection, and relationships that make us who we are, based on the extraordinary real life of Mary Leakey.