Northern Limit Line

Corporal Park Dong-hyuk, a fresh recruit in the Republic of Korea Navy, is introduced as he joins the patrol vessel PKM 357. His assignment occurs amid rising tensions along the Northern Limit Line, a crucial maritime boundary that becomes increasingly volatile.

As the excitement of the 2002 FIFA World Cup sweeps through South Korea, underlying tensions grow due to North Korea's covert operations. The North employs fishing trawlers to smuggle spies into South Korean waters, thereby attempting to gather intelligence.

The crew of PKM 357 begins intercepting fishing vessels that exhibit suspicious behavior along the maritime boundary. These encounters lead to alarming discoveries, allowing North Korean operatives to gain insights into the design and operational methods of the South Korean Navy.

Following the initial interceptions, the North Korean Navy ramps up its incursions into South Korean waters. These repeated reconnaissance missions aim to analyze and exploit the ROK Navy's patrol strategies and defensive capabilities, increasing the sense of urgency for action.

Despite alarming intelligence reports regarding the North Korean incursions, the South Korean Ministry of Defense faces bureaucratic obstacles. Directives from the Blue House hinder proactive military actions, leaving the forces in a precarious situation.

Lieutenant Commander Yoon Young-ha, commander of PKM 357, urgently issues warnings regarding the increasing threat from the North. His pleas for a reassessment of engagement rules unfortunately go unnoticed, setting the stage for the upcoming confrontation.

On June 29, 2002, North Korea launches a surprise offensive against PKM 357, significantly escalating the conflict. The sudden attack results in a fierce naval battle, with both vessels suffering devastating damage as they engage in combat.

The battle leaves a tragic toll on both sides, with 19 South Korean sailors injured and 4 confirmed dead. The ferocity of the skirmish results in PKM 357 being overwhelmed by flames, highlighting the grave danger faced by those aboard.

In the aftermath, divers later discover the lifeless body of the helmsman, tragically entangled in the wreckage of the sunken PKM 357. This discovery underscores the personal cost of the conflict and the sacrifices made by the crew.

Eighty-three days after the battle, Corporal Park Dong-hyuk succumbs to his injuries, marking him as the last casualty of the Battle of Yeonpyeong. His passing adds to the somber legacy of the conflict and the pain experienced by his comrades.

As the film concludes, the surviving crew members of PKM 357 gather to honor their fallen brothers. They come together around heartfelt photographs, reminiscing and paying tribute to those who bravely sacrificed their lives in service to their country.