根據韓戰期間真實戰事改編。1950年6月25日，北韓揮軍越過三八線突襲南韓，三日攻陷漢城（今首爾），戰線不斷南進。在美軍及聯合國軍支援下，南韓軍逆勢反擊。美軍指揮官麥克亞瑟提出代號為「鐵鉻行動」的仁川登陸計劃，該計劃急需一支大隊的兵力從側翼阻擊擾敵、聲東擊西，通過長沙里切斷北韓軍的補給線。　　由于任務本身極其艱钜，加上南韓國軍當時兵力薄弱，無法抽調足夠正規軍支援，軍方不得不把這項任務交付給772名學生兵執行，這些學生兵平均年齡只有17歲，僅僅接受了兩星期的軍事訓練，在毫無實戰經驗的情況下投身戰場。行軍路上固然殺機重重，戰友内部也諸多衝突，年少氣盛，迸發出各種角力。　　仁川登陸戰前夕，長沙里登陸任務如期執行，這群徒有一腔熱血但戰力薄弱的學生們，無可避免地接受命運中最殘酷的考驗：穿越炮火與海浪，浴血長灘，馀下部隊身陷敵軍重重圍剿，直至彈盡糧絕，掙紮于陣亡與倖存的分界線上…　　Based on the incredible true story of Jangsari Landing Operation. When North Korea invades South Korea on June 25, 1950, they pushed South Korea and its ally US Army to the southernmost city. U.S. General MacArthur planned Operation Chromite, which would see the joint allied forces to take back a strategic location of Inchon and in order for it to succeed, he needed a small battalion to flank the North Korean army and eliminate their supply line at Jangsari beach.　　Having lost his family on his retreat away from North Korea before the War, a model student Choi Sung-pil enlists in the army to fight for the South. Ki Ha-ryun is a rebellious youth from the South who volunteers to fight in the war. All of the 772 students and youths are like them who are barely out of school with only 2 weeks of boot camp training. Task force commander Captain Lee Myung-jun knows that it’s a long shot, but he has no choice but to lead them into a crucial mission. Meanwhile, US war correspondent Maggie braves the dangers of the battlefield to report on the war in the frontlines. She feels empathy for the Korean students who must go into battle on behalf of the veteran soldiers for their country, and tries to do what she can on her end to rescue them.　　With little ammo, scant food supplies and raggedy weapons, can the students successfully carry out their mission and return home safely?