As World War II escalated in 1943, Major Keith Mallory and Sergeant Donovan "Dusty" Miller, part of the British Army's elite Special Forces, also known as commandos, set forth on a dangerous mission to track down Nicolai, a deceitful Nazi spy who had previously betrayed the critical Guns of Navarone operation in Greece. Now hiding under the alias "Captain Lescovar", Nicolai was suspected of having successfully penetrated the ranks of the anti-Nazi communist guerrilla forces in Yugoslavia. The duo's journey led them across the Adriatic Sea from Allied-occupied southern Italy into the treacherous Balkans Mountains.
Joining their cause was Force 10, a U.S. Army sabotage team led by Lieutenant Colonel Mike Barnsby, and they even commandeered a British Royal Air Force Lancaster bomber from an airfield. Alongside them was Weaver, a sergeant from the U.S. Army Medical Corps who had escaped custody after being arrested for desertion, and Lieutenant Doug Reynolds, who miraculously survived a Luftwaffe attack on their aircraft. Only five men—Barnsby, Mallory, Miller, Weaver, and Reynolds—managed to escape the airplane wreckage, but their predicament was far from over.
After crash-landing in unfamiliar territory, they encountered individuals they believed to be Yugoslav Partisans, only to soon realize their mistake; these men were actually Chetniks, pro-German forces that posed a severe threat. Captured by Captain Drazak and his Chetnik unit, the commandos were forced to devise a plan to hide the explosives contained within Miller's suitcase. Mallory cleverly misled Major Schroeder by asserting that the suitcase held newly developed penicillin which would spoil if exposed to air, preventing him from uncovering the truth about the explosives inside. The following morning, under the guise of medical necessity, Mallory and Barnsby were sent to gather the "samples" with the guidance of Maritza, a guerrilla fighter who was actually Drazak's concubine.
Maritza’s unexpected betrayal revealed her as a bona fide Partisan, skillfully redirecting Mallory and Barnsby to her father's camp, commanded by Major Petrovich. In a twist of fate, they managed to discover another group of true Yugoslav Partisans led by Lescovar, who had gained Petrovich's trust. As they arrived at the camp near a hydroelectric dam, they identified a pivotal structure – a bridge that the Germans intended to use for an imminent attack on the Partisans. Barnsby revealed that this bridge was, in fact, the target of Force 10's mission.
Mallory persuaded Petrovich to launch a rescue mission for Miller. Disguised as captives, Mallory and Barnsby infiltrated the Chetnik camp under the cover of night, accompanied by Lescovar and Marko, posing as their captors. When Captain Drazak discovered Maritza’s duplicity, he brutally attacked her, but ultimately Mallory and the others escaped with a wounded Maritza and the crucial explosives. Upon returning, however, Miller expressed concern over the bridge's defensive capabilities, but Barnsby remained steadfastly determined.
Mallory devised an ingenious alternate plan: rather than attacking the bridge directly, they would destroy the dam upstream, unleashing a catastrophic rush of water to sweep away the structure. They coordinated a nighttime parachute resupply with Allied Air Forces, yet Lescovar, the saboteur, alerted German forces to the operation. Maritza attempted to expose him but tragically lost her life in the process. As German aircraft bombed the drop zone, tension mounted.
Following Petrovich's orders, their plans to return to Italy were disrupted by Lescovar's treachery yet again, culminating in a bold raid on a German railroad yard to steal explosives. Tragically, Marko sacrificed himself to save his comrades during their escape aboard a train to Sarajevo, with Lescovar still lurking among them. Their suspicions about Lescovar's loyalty were ultimately confirmed when Barnsby dealt with him decisively, allowing the team to focus on the mission ahead.
As they approached the dam, they split into two teams: Miller and Weaver created a diversion, while Mallory and Barnsby executed their covert operation within the dam. In a harrowing confrontation, Weaver faced off against Captain Drazak, ultimately killing him in a fierce knife fight. Meanwhile, Mallory and Barnsby successfully rigged their explosive charges within the dam, resulting in a massive collapse that obliterated the dam and the bridge downstream, halting the impending German offensive.
Following this monumental victory, the team regrouped but soon realized they were trapped on the other side of the river, with no clear path back to safety. As the credits rolled, they began a strenuous trek towards Allied territory, their fates hanging in the balance amid the dangers of war.
