Oil prospectors Rolf and Robert travel to an outpost in a jungle on the Mindanao. A rough landing damages the plane. Robert and Rolf find the abandoned remains of the original prospecting camp. They then find a rotting corpse and determine the prospectors were massacred by natives. Later, a member of the team, Swan goes missing. The two prospectors and their pilot Charlie go into the jungle, and the pilot is killed by a booby trap resembling a giant mace. Robert and Rolf then see Swan's remains being eaten by cannibals. After building a raft in order to float down river to get back to the airfield, Robert and Rolf are separated when the raft is destroyed after traversing rapids. Robert, lost in the jungle, eats poisonous mushrooms, then vomits and passes out. He awakens to find himself being poked and prodded with large spears wielded by the cannibals.