Eight-year-old adventure seeker Pete is convinced something mysterious is hidden in the school staff room. His ten-year-old sister, Trudy, who is much more practical, is not. But when adventure does appear in Mini Moa form, can the siblings work together to outsmart a fake substitute caretaker, or will she succeed in destroying their new friends' home and the school in one noisy go?

Eight-year-old adventure seeker Pete is excited to explore a mysterious nighttime noise. His ten-year-old, more sensible, sister Trudy, thinks it sounds much too dangerous. But when it turns out to be a friendly pegasus in need of the brave sibling duo, can they put aside their differences to beat a vain mountain creature, or will the beauty of the Southern Alps disappear for good?