Ellie Linton's call to adventure occurs when her and six of her friends return home from a week long camping trip to a large, vegetated sinkhole known as "Hell." During the camping trip the group sees a large number of military planes flying through the night without lights on. They talk about it the next morning, but don't think it's of much importance. When they return they find that all the people are missing and their pets and livestock are dead or dying. Fearing the worst, they break into three groups to investigate Wirrawee's situation. They confirm that Australia (or at least, Wirrawee) has been invaded and local citizens are being held captive by the occupying force.
"In the house nothing was wrong, and that was what was wrong. There was no sign of life at all. Everything was neat and tidy. At that time of day there should have been food spread out on the kitchen table, there should have been dishes in the sink, the TV should have been chattering in the background. But all was silent." (Marsden 56)