Corporal Rolf Steiner, a seasoned soldier serving in the Wehrmacht during World War II, finds himself entrenched in the brutal realities of the Eastern Front. Following a successful mission against an enemy mortar position, his reconnaissance platoon captures a young Russian boy soldier. As they make their way back to friendly lines, they encounter the newly appointed Captain Stransky, who takes command of Steiner's battalion. The regiment's commander, Colonel Brandt, expresses curiosity about Stransky’s sudden transfer from the more luxurious duties in occupied France to the harsh front lines of Russia. Stransky proudly proclaims that his ambition is to earn the Iron Cross.
Upon meeting Steiner, Stransky immediately orders the execution of the captured boy. However, in an act of defiance, Steiner refuses and has Corporal Schnurrbart hide the boy. Shortly thereafter, Steiner learns of his promotion to senior sergeant during a meeting with Stransky. It is in this tense atmosphere that Stransky realizes his adjutant, Lieutenant Triebig, is a closeted homosexual, a revelation that poses severe consequences in the German Army.
The platoon gathers to celebrate Lieutenant Meyer's birthday when tragedy strikes—Steiner attempts to set the young Russian free, but he is inadvertently killed by the advancing Soviet troops. As the chaos unfolds, the Germans find themselves scrambling to defend their positions. Overcome by fear, Stransky hides away in his bunker, while Meyer heroically falls during a counterattack. Subsequently wounded, Steiner is sent to a military hospital where he experiences vivid flashbacks and a brief romance with a nurse portrayed by Senta Berger. Opting for duty over rest, Steiner returns to his men instead of taking the home leave offered to him.
Upon his return, he discovers Stransky's dubious nomination for an Iron Cross, based on Meyer's actions during the counterattack. To validate his claims, Stransky resorts to blackmailing Triebig and attempts to manipulate Steiner into supporting his lies, promising preferential treatment post-war. Brandt hopes that Steiner will courageously expose Stransky’s deceit but, instead, Steiner expresses his general disdain for all officers, be they as "enlightened" as Brandt and Kiesel, and requests time to contemplate his decision.
When retreat orders are issued, Stransky neglects to inform Steiner’s platoon, leading them through perilous territory. During this tense journey, they capture an all-female Russian unit. In a horrific turn of events, the despicable Nazi Party member Zoll rapes one of the women, resulting in her death after biting him. Distraught and angered, Steiner confines Zoll with the Russian women, seizing their uniforms as a disguise.
As they approach the German lines, communication is established to prevent friendly fire. However, Stransky sinisterly suggests to Triebig that they allow Steiner’s group to be mistakenly identified as Russians, leading to a disastrous confrontation where only a few—Steiner, Krüger, and Anselm—survive. In a tempestuous turn of events, Steiner confronts and kills Triebig, promoting Krüger to platoon leader, instructing him to safeguard Anselm.
With the Soviets mounting a formidable assault, Brandt urges Kiesel to evacuate, emphasizing the need for men like him to help rebuild Germany after the conflict. Brandt heroically attempts to rally the chaotic troops for a counteroffensive.
In a fateful encounter, Steiner tracks down Stransky but chooses not to take his life. Instead, he hands Stransky a weapon and offers to reveal "where the Iron Crosses grow." Stransky, seeing this as both a challenge and an opportunity, agrees to follow Steiner into battle. The film concludes with Stransky perplexed over how to reload his MP40 while dodging gunfire from a young Russian soldier who resembles the boy they had earlier released. In a moment of dark humor, when Stransky asks for assistance, Steiner laughs, a haunting sound that echoes as credits roll alongside the song "Hänschen klein," juxtaposed with stark black-and-white images of the civilian cost of war.
