Showing Tomorrow, When The War Began by John Marsden

Seventeen-year-old Ellie Linton wants one final adventure with her friends before the school holidays are over. Packed in Ellie's parents' land rover they drive to the famously isolated rock pool Eden dubbed 'Hell' by the locals. Returning to their home town of Wirrawee, the seven teenagers realize that something is seriously wrong. Power to the houses has been cut, pets and livestock have been left dead or dying, and most alarmingly of all, everyone's family has vanished. When the hostile armed forces discover that the teenagers are lying low in the vicinity, Ellie and her friends must band together to escape, outwit and strike back against the mysterious enemy that has seized control of their town and imprisoned their friends and loved ones...