Deep in the heart of the island of Borneo is a lost world of mountains, jungles and ravines. It hides a vast abundance of wildlife. But it is disappearing — fast.

The Discovery Channel has assembled a team of jungle specialists — scientists, climbers and wildlife filmmakers — to explore this extraordinary habitat before it's too late. Tropical timber harvesting and clearing the land for oil palm plantations are threatening this unique ecosystem.

The expedition's aim is to track down and film the amazing animals that live in this wilderness. The scientists' hope is that the evidence they collect will help in the struggle to conserve this region forever.

First stop is Imbak Canyon, a remote valley covered in virgin rain forest and protected on either side by steep walls of rock. The team members are living in a base camp deep in the jungle. The camp is basic and must serve as laboratory, living quarters and command center.

It is a tough place to live and work — as hot as a sauna and just as humid. Leeches have to be picked off the body constantly and the smallest cuts quickly turn infectious. Rainforest trees come crashing down in the tropical storms and one narrowly misses base camp.

After four weeks, the team has found more than 100 species — many never recorded in this area before.

During Phase 2 of the expedition the team moves even deeper into the heart of Borneo. One team travels up remote rivers rarely seen by outsiders, where they find caves with extraordinary rock art painted by ancient forest peoples more than 10,000 years ago.

The second team makes a daring descent into a gigantic collapsed cave. In its confines,  they squeeze through terrifyingly small gaps to discover a whole new system of cave chambers never seen before by humans.

The scientists are joined by a team of local naturalists, ex-army medics, and the production team of camerists,recordists, expert tree and rock climbers and film directors.