Into the Fire South Korean student Oh Jang-beom is a volunteer militia soldier during a battle in Yeongdeok, North Gyeongsang Province during the Korean War. When the city is surrounded by the 766th Unit, 5th Division, Korean People’s Army, he is pulled into a squad consisting of South Korean soldiers led by Lieutenant Kim Jun-Seop who is trying to escape. The unit is eventually reduced to only Lieutenant. Kim and Jang-Beom. A North Korean suddenly shoots and bayonets the lieutenant. Jang-beom, because of his inexperience and terror cannot save his friend. They are rescued by fellow South Koreans, and barely make it onto one of the last trucks out of the town to an emergency hospital in Pohang which is where Lt. Kim dies with a guilt-ridden Jang-beom at his side.
Capt. Kang commands Jang -beom, one of three combat veterans to head the newly-established student soldier unit. Three young criminals under the leadership of Ku Kapjo, join the unit , and destroy students’ food supply. While on patrol, they are attacked by the KPA Sniper who takes the group to an ambush. Before disengaging, the students are stricken with heavy injuries. The tragic incident shatters the students morale. Students call Capt. Kang and ask for help, but regular forces are confined to the Nakdong River. Kang appeals to his superiors to aid pupils, however they are unable to divert resources away from the crucial Pusan front. They dohowever allow Kang to go and he gathers vehicles as well as a tiny force of South Korean soldiers to relieve the school. Into the Fire HD
One of the soldiers, Dal-Young, is captured by the 766th Unit and is interrogated by Major Park Mu-Rang. Mu-Rang feels sorry for this student and asks him to return to his school. He will also go there to evaluate the strength of the students. He then informs Jang-Beom that he and his men will in two hours, capture the school. He also offers to spare the attackers their lives if they wave a white flag. Kap-Jo defeats Jang-beom and fights him off before departing with a friend Chang-wu for the Pusan Peridometer. Soon after departing, the two run into an North Korean truck filled with supplies and weapons, stuck in a road.
As Major Park prepares for an attack, the remaining students prepare to defend their school by waving not a white flag but the South Korean flag. The assault begins and the students are able to cause serious casualties to North Koreans but are eventually forced to withdraw. Suddenly the North Korean supply truck roars into the scene, driven by Chang-wu and Kap-jo, carving their into the North Koreans, halting their attack as well as providing valuable guns to the pupils.
The 766th’s men go into the school under the cover of tanks and massacre the students. Jang-Beom and Kap-Jo fight to take on the North Koreans inside the building until they reach the top of the building, from where the other soldiers have installed machine-guns. Jang-beom, Kapjo and others attempt to stop the North Koreans from reaching the roof.
As Jang-beom, Kap-jo and Jang-beom are running out of ammunition, Capt. Kang and the South Koreans arrive. They take out the North Korean tank and steadily defeat the North Korean infantry in the school campus. In the roof, while Jang-beom collapses from exhaustion and his woundsare healing, Major Park arrives and kills Kap-jo. While Park exults, Jang-beom humbly fires his gun and shoots Park exactly while Park is also shot at. Later Capt. Kang. Kang offers comfort to Jang-Beom while he is dying from his injuries.
The film reveals that of the 71 students, 48 died defending the school. The movie ends with a flashback, with an Army photographer taking a group picture of the student-soldiers before the regular troops leave for Pusan, and the surviving student-soldier veterans, now old and aging, reflect on their experiences.