Alan Dean Foster 
Primal Shadows 

When his wallet is lifted from a one-night stand with an exotic young woman, who may be either the girl of his dreams or just a common third-world grifter and thief, this world-weary traveller decides to go against his own better judgement and that of the local authorities and pursue this alluring thief up-country into the darkest jungles of Papua New Guinea.Here is a land where headhunters still roam, and where the natural obstacles of poisonous insects and reptiles, savage and deadly beasts, and the mortally demanding jungle itself are the least of his worries. The forces of good and evil and law and anarchy play by entire different rules in this shadowed world.Driven by delusions of romance and the need to restore his honour, Bohannon moves in hot pursuit farther and farther up-country, into a heart of darkness almost untouched by modern civilization. And once he attains his immediate goal, he is drawn into the darkness of his own soul, as a hunt for gold proves that greed, more than love or lust, is the primal instinct. For men or women, black or white, civilized or savage, in the darkness of the jungle all shadows are primal.