The Unexpected (Animorphs #44)

Cassie is on her own. There's no Jake to lead the mission. No Marco to tell stupid jokes. And no Rachel to say "Let's do it!" It's just Cassie. Alone. In Australia. It all began when the latest Animorphs' mission took a bad turn–and Cassie hid in the cargo hold of a jumbo jet. Unfortunately for her, that jet took off, bound for Australia. And what Cassie didn't realize was that the Yeerks were still on her trail–a lone "Andalite bandit" is a pretty hot target. Cassie ends up in the Australian Outback–with no friends to help her, and no knowledge of the terrain. Even worse, she doubts her survival skills are strong enough to get her back home. Especially when she notices someone else who's not exactly from the Outback. Visser Three.