Tom Hart Dyke is traveling through Central America in search of wild orchids. Paul Winder is in search of adventure. Together they attempt to cross from Panama to Colombia via the notoriously dangerous Darien Gap, but are captured and held hostage by a revolutionary guerrilla group. With a $3 million ransom placed on their heads, they realize that their only chance of survival is to escape. But any plans to make a dash for it are shattered when Tom discovers maggots have infested his leg.