During a period of sluggish economy and high unemployment, four friends—Stone James Brolin, Tony Chick Vennera, Dan Bruce Davison and Rockney Cleavon Little—gather for a fishing trip that doubles as a plan to fly to Colombia to rob a drug lord. They meet Clint Ernest Borgnine, who supplies them with weapons and target practice. It becomes clear that with the exception of Stone, the men have little training and are not taking the heist seriously.
The group is flown into a jungle, where their target, Serrano [James Coburn], a sadistic drug lord who presides over a sprawling villa, looms as the central obstacle. From a hidden vantage point, they study Serrano, his staff, and a rotating cast of visitors, debating what kind of courage would be required to kill and what they would do with their share of the cash once back home. They infiltrate the villa, capture Serrano and his lover, and force Serrano to reveal the safe’s combination. They escape with five million dollars in cash, moving on foot through the dense terrain until they can buy horses. They celebrate their apparent success, unaware that a rebel tracker is watching their every move.
The following morning, Serrano’s men and local military forces close in with all-terrain vehicles and mounted troops. The group flees, but Tony and Rockney are captured by Serrano. Stone and Dan push ahead on foot and manage to escape their pursuers only by leaping from a very high rope bridge. Serrano’s men force Tony to reveal the location of the money, knowing Stone has his share and calculating better odds of survival if they move into the open.
Captured and taken to a prison, they meet Olivia [Lindsay Wagner], a prisoner in the neighboring cell who insists she was falsely arrested. Tony bribes a passing child to pull out the barred window with a tow truck, but the child demands their clothes in payment as well, sending the group fleeing through town almost naked until they slip into a bordello. Disguised in women's clothes, Tony and Rockney make their way to a bus station and join Olivia as they head toward the rendezvous point.
Meanwhile, Dan and Stone fall into the hands of a local rebel commander, General Mariano [Anthony Quinn], who intends to claim the stolen money for himself. They manage to escape his grip, then pursue the rebels, fighting their way through the night to retrieve the cash. The rebels press them toward the rendezvous as a firefight erupts; Dan is wounded by Mariano’s tracker, and Tony is shot while trying to shield Stone.
Believing Tony to be dead, the remaining trio presses on toward the airstrip. Serrano’s mercenaries reach the scene first, sparking a three-way gun battle. The rebels are overwhelmed, the retrieval plane finally arrives to provide covering fire, and the team boards in a frantic rush. They get away, celebrating their success—only to have the engine stall just as the escape craft lifts off, leaving their fate hanging in the balance.
