Trekking with their eco-photographer parents, Amy and Christopher suspect a thief on New Zealand's famous Milford Track. 

Is it Ms Tree, the Freedom Walker? Other suspects include a keen golfer, a rugby international and Zoe, the guide. When a mischievous kea bird steals from the twins, they change their minds. Dr Al, the celebrity explorer is being filmed on the Track, by their parents. Could he be involved in illegal kea or nugget smuggling? 

Backpack mix-ups, a loo-with-a-view and a kea copy-watch contribute to this heli-hiking mystery set in New Zealand. The Frequent Flyer Twins are nearly 'fleeced' by a nugget smuggler.