Two fearless women—living a century apart—find themselves entangled in the mystery surrounding the biggest scientific controversy of the nineteenth century: the classification of the platypus.

1808 Agnes Banks, NSW

Rose Winton wants nothing more than to work with her father, eminent naturalist Charles Winton, on his groundbreaking study of the platypus. Not only does she love him with all her heart but the discoveries they have made could turn the scientific world on its head. When Charles is unable to make the long sea journey to present his findings to the prestigious Royal Society in England, Rose must venture forth in his stead. What she discovers will forever alter the course of scientific history.

1908 Sydney, NSW

Tamsin Alleyn has been given a mission: travel to the Hunter Valley and retrieve an old sketchbook of debatable value, gifted to the Public Library by a recluse. But when she gets there, she finds there is more to the book than meets the eye, and more than one interested party. Shaw Everdene, a young antiquarian bookseller and lawyer, seems to have his own agenda when it comes to the book. Determined to uncover the book's true origin, Tamsin agrees to join forces with him.

The deeper they delve, the more intricate the mystery of the book's authorship becomes. As the lives of two women a century apart converge, discoveries emerge from the past with far-reaching consequences in this riveting tale of courage and discovery.