This is an adventure story set in Malaysian Borneo. Choco-Snaps Cereals and Flyaway Airlines run a competition offering a once in a lifetime holiday. The winner, twelve year old Amy Applegate, accompanied by her best friend George, chooses to visit orphaned orang-utans. They pack their gadget filled penknives and leech socks and head for Asia. They are looked after by local guide Izzy, who takes them on many adventures including the exploration of bat-filled caves and encounters with deadly reptiles. She also arranges a stay with an Orang Ulu tribe at a traditional longhouse. From their host Terangu, they learn the secrets of poison darts and animal tracking. However, one animal eludes them. Where are the long-nosed monkeys? At the longhouse, the fun of firing blowpipes and eating dragonflies with ginger gives way to fear as a mysterious event tests their bravery and friendship in the face of adversity. Will they be able to solve The Primate Puzzle before it is too late?