The Last Flight of the Kingfisher

Fifteen-year-old Luke Ralston knows his mother's fortnight with the kids is not supposed to end in the Borneo rainforest. Elaine Ralston, a disgraced balloon engineer, has smuggled Luke and his little sister Amy up the Baram River to a remote limestone ridge, where she is building a hydrogen airship in a giant tree. Then chainsaws start cutting into protected forest, a hired pilot arrives with a Texas court order, and Luke must decide who to trust.