When the first specimen of a platypus arrived in England in 1799, it was greeted with astonishment and disbelief. What was this strange creature from the new colony of Australia? It defied rational explanation, with its webbed feet and duck's beak attached to what seemed to be a mammal's body - surely it was a hoax on the part of those cheeky new colonials? As 18th-century naturalists struggled to classify the platypus, the little animal excited curiosity and sparked fierce debate in international scientific circles, drawing in leaders of zoology and comparative anatomy in Britain and Europe. This is the enigmatic story of a biological riddle that confounded scientists for nearly 90 years, challenging theories of creationism, evolution and the classification of species along the way. Secretive, elusive and beguiling, the platypus has continued to captivate public and scientific attention to the present day.