An American fashion photographer, Ben Morris (James Garner), goes to Guadagil, a remote village in South America, to take pictures of model Alison Duquesne (Eva Renzi) for a lipstick ad. (One of the lipsticks is called "Pink Jungle".)
She arrives soon after Ben does, escorted by Raul Ortega (Michael Ansara) from the tourist board. Within minutes of being landed the helicopter in which they arrived is stolen, leaving Ben and Alison stranded in the village.
Ben is hassled by Colonel Celaya (Fabrizio Mioni), a security officer anxious to get a promotion to the capital, who is convinced Ben must be a spy for the American government. But a search of his baggage finds only camera equipment and lipstick. Ben and Alison go to the town bar, where they are joined by Ortega. Meanwhile, two thugs assault and kill the helicopter driver, wanting information on how it had come to be stolen. The thugs are joined by Ortega, who is revealed to be their leader.
To relieve their boredom Ben and Alison rent a car to drive to the nearest town. On their way the car is stopped at gunpoint by the same man who stole the helicopter. He forces them to take him with them. The hijacker is a boisterous South African adventurer Sammy Ryderbeit (George Kennedy). He tells them he and his partner have a map to a fabulous diamond mine, but they need $2,000 to equip an expedition to get there.
In a bar in town Ben and Alison meet with Sammy’s partner, an English ex-army man Captain Stopes. Also in the bar are Ortega and his men. Ben and Alison believe the entire tale of the diamond mine is a scam. However, when Stopes is murdered in his hotel room, with Ben and Alison and Sammy suspected and pursued by the police, Ben is compelled to finance the diamond mine expedition merely as a way for he and Alison to sneak out of town. They are watched doing so by Ortega and his men.
Along the trail Ben, Alison and Sammy encounter McCune (Nigel Green), a devious Australian who claims to be Stopes's former partner and says he has the only actual map to the mine. He surreptitiously substitutes Sammy’s map for his own, which he pretends is the one he has always had. McCune demands to take over the leadership of the expedition, in return he will give the others a small share in the mine. Although they distrust him, the three reluctantly agree. While resting up for the next day’s march all the men posture about, demonstrating excellent marksmanship with pistols.
Almost immediately after they resume their search the men start fighting with each other. That night McCune demands that the men allow him to bed Alison. Sammy says nothing, but Ben will not allow it and he and McCune fight it out. Ben and Alison have a private conversation in which they admit to having fallen in love with each other. Later that night McCune sneaks out of camp to leave a message, along with the map he tricked out of Sammy, along the trail.
During the next day the expedition pauses to rest out the sun’s hottest hours. While the others are asleep McCune takes off with the supplies and mules, leaving them to die of thirst. But he is pursued by them, and when he takes a wrong turn it allows them to catch up with him. He hears them coming and takes up a position to shoot Ben, but just as he is about to fire he is shot dead by Sammy.
They search McCune’s body for the map, and not finding it realize he must have left it for others. Just then a helicopter is heard and seen flying overhead. The three proceed to where the helicopter had landed, and see Ortega sitting in front of a tent counting diamonds. The helicopter arrives again, bringing in more diamonds, but this time the men flying in have seen the three. The members of the helicopter party spread out to attack them, but in the shootout that follows the three prevail and Ortega is captured.
Sammy flies Ben and Alison (and Ortega, their prisoner) back to Guadagil, saying he knows someone there who will buy the diamonds and pay in American dollars. But as soon as the others exit the helicopter he takes off, with all the diamonds. Ortega turns out to be an underground leader long wanted by local law officials. They are so satisfied in at last having him in custody that they don’t care about anything Ben and Sammy may have done.
Ben and Alison are desperate to leave. Ben talks to the jubilant Colonel Celaya, who has taken the credit for having captured Ortega, hoping the officer will arrange to have them flown out. The colonel will not help with that, but does say he is sorry for having when they first met mistaken such a bungler as Ben for a CIA agent.
Ben walks to a private spot, converts his camera into a two-way radio, and sends a message to his contact person. Ben is not just a photographer, he is a U.S. government agent sent to quell a revolution led by Ortega. Because of Sammy's assistance in accomplishing the mission, Ben allows Sammy to get away.James Garner as Ben Morris
Eva Renzi as Alison Duquesne
George Kennedy as Sammy Reiderbeit
Nigel Green as McCune
Michael Ansara as Raul Ortega
George Rose as Stopes
Fabrizio Mioni as Coronel Celaya
Vincent Beck as Sanchez
Val Avery as Rodriguez
Robert Carricart as Benavides
Natividad Vacío as Figueroa