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鉅，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，戰友內部也諸多衝突，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，掙扎于陣亡與倖存的分界線上…BasedontheincredibletruestoryofJangsariLandingOperation.WhenNorthKoreainvadesSouthKoreaonJune25,1950,theypushedSouthKoreaanditsallyUSArmytothesouthernmostcity.U.S.GeneralMacArthurplannedOperationChromite,whichwouldseethejointalliedforcestotakebackastrategiclocationofInchonandinorderforittosucceed,heneededasmallbattaliontoflanktheNorthKoreanarmyandeliminatetheirsupplylineatJangsaribeach.HavinglosthisfamilyonhisretreatawayfromNorthKoreabeforetheWar,amodelstudentChoiSung-pilenlistsinthearmytofightfortheSouth.KiHa-ryunisarebelliousyouthfromtheSouthwhovolunteerstofightinthewar.Allofthe772studentsandyouthsarelikethemwhoarebarelyoutofschoolwithonly2weeksofbootcamptraining.TaskforcecommanderCaptainLeeMyung-junknowsthatit’salongshot,buthehasnochoicebuttoleadthemintoacrucialmission.Meanwhile,USwarcorrespondentMaggiebravesthedangersofthebattlefieldtoreportonthewarinthefrontlines.ShefeelsempathyfortheKoreanstudentswhomustgointobattleonbehalfoftheveteransoldiersfortheircountry,andtriestodowhatshecanonherendtorescuethem.Withlittleammo,scantfoodsuppliesandraggedyweapons,canthestudentssuccessfullycarryouttheirmissionandreturnhomesafely?

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