Mary Poppins is a publishing phenomenon of eight books written across 55 years, translated into 20 languages, including Swahili. The 1964 Disney film starring Julie Andrews remains one of the most popular children's movies of all time. Yet the author did not want it to be known whether she was 'man, woman or kangaroo'. The elusive PL Travers was, in fact, born in outback Australia in the penultimate year of the 19th century. She became a pioneering journalist in Russia, wrote propaganda for the war effort in New York, lived on a Navajo Indian reservation and was only the second Western woman to study Zen in Kyoto. Deeply spiritual, as one of the inner sanctum of the mystic GI Gurdjieff, she wanted to communicate through Mary Poppins more than carpet bags and parrot umbrellas. With new source material taken from interviews with PL Travers' family and friends, this biography shares a new perspective on this extraordinary and complex author.