Two mates on a boy's own adventure with a twist!John Doyle is a city boy who's never been to the outback. His mate, Dr Tim Flannery, is one of Australia's leading scientists who knows the bush like the back of his hands. For years, they have been taking boating trips together but until now their expeditions have been confined to exploring the nooks and crannies of the Hawkesbury River aboard the Bismarck, Tim's 3-metre aluminium 'tinnie' that has only been sunk once - by John.John has a passion for bird watching and astronomy; Tim has an astounding knowledge of anything and everything including palaeontology, geology, history - and the location of the best outback pubs! These two mates share a sense of humour and love of a good yarn. Now they've decided to head further a-field and take the Bismarck on a journey into the heartland of Australia, to unravel the secrets of our greatest river system. John is intrigued and troubled by the problems in the bush, so they hatch a plan to investigate them first hand - and undertake a glorious adventure along the way, passing through some of Australia's most picturesque landscapes. Their journey takes them along the two great arteries that sustain the very heart of the country - the Murray and Darling Rivers, from the source of both rivers all the way to the sea. They travel from the Darling Downs in Queensland to the junction of the two rivers at Wentworth, then from the Snowy Mountains down the Murray to South Australia. At a time of drought, global warming, population pressures and fights over water rights, this trip gives John and Tim the opportunity to meet the people and visit the places that reveal the trials and tribulations of the Murray-Darling. As they motor along the rivers, John and Tim discover how the rivers have shaped the Australian people and how the people have shaped the rivers. This series is a quest to understand the past, present and future of the Australian continent.