| Director | Guy Hamilton |
|---|---|
| Budget | $10.5 million |
| Box office | $3.2 million |
In 1943, following the destruction of a German fortress on the island of Navarone, Major Keith Mallory and Sergeant Donovan "Dusty" Miller are ordered to eliminate the German spy who betrayed the Navarone mission. The spy is believed to have infiltrated the Yugoslav Partisans under the assumed identity "Captain Lescovar". Mallory and Miller are attached to "Force 10", an American commando unit led by Rangers lieutenant colonel Mike Barnsby. They steal a Royal Air Force bomber, joined by Weaver, a U.S. Army Medical Corps sergeant who has escaped Military Police custody. When the bomber is intercepted and forced down over Yugoslavia, only Barnsby, Mallory, Miller, Weaver, and Lieutenant Doug Reynolds survive the crash.
The survivors are captured by pro-German Chetniks led by Captain Drazak. They tell a German army commander, Major Schroeder, they are actually deserters and that Miller's suitcase, stuffed with high explosives and sabotage gear, contains penicillin which will spoil if exposed. when Schroeder later reveals he opened the case and found only firewood, the commandos claim they buried the drug samples. Schroeder sends Barnsby and Mallory to retrieve them, guarded by his concubine Maritza and three soldiers.
Far from camp, Maritza kills the Germans, reveals she is a partisan and admits to hiding the explosives. She directs Mallory and Barnsby towards a camp commanded by her father, Major Petrovich, but encounter a partisan patrol led by Lescovar which takes them to their camp near a hydroelectric dam. An arch bridge spanning the river ravine will be used by German forces for an impending assault on the partisans. Barnsby reveals the bridge is Force 10's actual target.
Mallory, Lescovar and Marko infiltrate the Chetnik camp disguised as Chetniks escorting captives, in order to rescue Miller. Drazak discovers Maritza helped Miller and Mallory escape and beats her. Schroeder and Reynolds are killed in a firefight, but the others escape with a badly hurt Maritza and the explosives. Miller assesses the explosives as too weak to destroy the solidly built bridge and Mallory suggests demolishing the upstream dam in order to destroy the bridge. An air resupply is arranged, but Lescovar calls for German planes to intercept it. Maritza discovers Lescovar's treachery and is killed before she can warn the others.
Angered by the botched air drop, Petrovich orders the men to be sent to partisan commander Tito's headquarters for transport back to Italy. Accompanied by Lescovar and Marko, the team instead infiltrates a German marshaling yard to steal explosives. Lescovar alerts a German sergeant to their presence. Marko sacrifices himself so the others can escape with Lescovar aboard a train for Sarajevo. Lescovar is questioned, gives himself away and is shot dead by Barnsby, who asks Mallory to return the favour by helping him accomplish Force 10's original mission.
Jumping the train near the dam, the team splits up: Miller and Weaver run a diversion using various gadgets from his briefcase, while Mallory and Barnsby sneak into the dam. Weaver kills Captain Drazak in a knife fight. Mallory and Barnsby blast the concrete dam, and it bursts, releasing a torrent of water that topples the bridge. The German assault is thwarted, saving Petrovich and the partisan guerrillas.
Mallory and Barnsby rejoin Miller and Weaver on the wrong side of the river, and the men begin a strenuous journey back to friendly territory.