Dan Coltrane, Asio field agent for the Australian government and Interpol crime investigative officer meets his nemesis from a previous encounter while in London working on a code break-in case involving confidential government information. He discovers that the United Displaced Persons organisation working out of Eastern Europe is intent on forming an invasion fleet of homeless immigrants ready to embark on a journey across the Indian Ocean to Western Australia. Coltrane alerts the defence forces in Canberra but they are too late to intercept the initial UDP attack plan, hydrogen bomb weaponry to be used in five Australian capital cities. Two of the bombs are successfully dropped on Perth and Canberra before the defence of the nation is alerted and a plan is implimented by the Australian defence minister and his departmental heads. The state of Western Australia has to be evacuated quickly and the population as a whole embarks on a thousand mile journey to South Australia. They temporarily leave their home state ensuring it is devoid of water, food, fuel and shelter in order to deter the invading force. The temporary evacuation is the primary defence strategy and although it is inhumane in one sense, the harsh desert environment becomes a shield against the invaders without the need for military intervention. The story's conclusion will bring home the ever-present threat of nearby countries that eye our island nation with envy and desire.