Clode sets out to investigate a creature that is both loved and scorned, with populations withering towards extinction in some places while exploding in others. In following her own curiosity - from meeting koalas at Cleland Wildlife Park to caving on the Yorke Peninsula to better understand the fossil record - Clode engages the reader's curiosity too.

The book is a journey at multiple scales: through time and perspective, and from the breadth of landscape to the detail of microbiology. Delving into the deep past we learn that koalas are the smallest and only surviving representative of around 20 koala-type creatures that have existed over millennia, and that population size and distribution of the modern koala have expanded and shrunk through time.

Ecology helps us understand why koala populations have fluctuated so wildly, while Clode draws on biology to create a window into how a koala perceives the world. She makes microbiology accessible to the lay reader - observing "poo inoculation" and explaining the fascinating relationship between koala food and the specificity of their gut microbiome. Recent discoveries in this area help explain why koalas can fail to thrive when moved to new areas, even when given access to the same species of eucalypt.

Throughout, Clode grapples with the challenges of understanding another species, and with humanity's tendency to relate the perception, behaviour or intelligence of other animals to our own. "In the evolutionary race to supremacy, koalas are regularly pitched as having made poor choices ... they are described as slow, stupid and often considered incapable of change," she writes. Clode shows why these assumptions are erroneous and limit our ability to understand koalas as a species and as individuals. The numerous stories of koalas accepting help from humans indicate an awareness of the potential of humans to be useful that most wild animals don't perceive.

At times Clode's choice of anecdote is a little laboured, but in most cases the narrative thread does an excellent job of enlivening some very complex science. The power of Clode's observations strengthen as the book proceeds and she tackles the pressing issue of climate change. The author is, like all of us, now directly witness to environmental change - the impact of bushfire in the final section is powerfully wrought and painfully familiar.

Koala helps to unpick the mystery of koalas through a richly layered but completely accessible exploration of this unique mammal and its complex ecology.