After a failed attempt to bring the powerful chairman Lee Chan-young of the notorious Sangin Group to justice, prosecutor Han Ji-hoon finds himself demoted to a more undervalued position within the legal support office of the NIS. Undeterred despite the setback in his career, Ji-hoon eagerly takes on an assignment that his superior has shunned, leading him to a covert inspection of the NIS Shenyang branch, which operates as a secret base dedicated to high-stakes black operations involving North Korean counterintelligence.
At this classified facility, the Black Team, led by the formidable Ji Kang-in and masked under the façade of Samjin Travel Agency, is embroiled in a web of intrigue and danger. Tensions run high as Ji-hoon inadvertently annoys Kang-in by messing with an operation. In a dramatic twist, Kang-in frames Ji-hoon for serious offenses, including prostitution and illegal drug use, testing Ji-hoon's ability to think on his feet. With sheer determination, Ji-hoon escapes through a hotel window where the preparations for his downfall had been set in motion, successfully passing Kang-in's harsh judgment and officially integrating into the team at their clandestine base.
As Ji-hoon delves deeper into the team's mission, he learns that they are tasked with extracting Moon Byung-uk, a crucial figure in Room 39 of the North Korean Central Committee—an institution implicated in safeguarding the Kim family's hidden fortune. Moon's intention to defect to South Korea triggers a series of high-octane events that spiral out of control as multiple factions chase him down for vital information. Despite the chaos, the Black Team manages to secure Moon's adult daughter, Ju-yeon. However, their grim intentions to extract information from her lead them to face a strong moral dilemma. Ji-hoon, thus, makes a pivotal decision to let Ju-yeon escape, knowing that her safety might be the key to achieving their goals.
The Black Team's pursuit leads them to a shocking twist, as they uncover that they have been baited by Yoshinobu Ozawa, orchestrating an elaborate plot that culminates in the brutal murder of Moon and the kidnapping of Ju-yeon. With the Chinese authorities closing in, the Black Team is forced to dismantle their operations, obliterating all traces of their activities at the travel agency and their secret base. Unwilling to abandon their mission, they regroup with a plan to rescue Ju-yeon from the clutches of the Japanese consulate.
In a gripping turn of events, Ji-hoon successfully escapes with Ju-yeon, who possesses critical information regarding her father's hidden data. Under grave threats from Ozawa regarding his family's safety, Ji-hoon teams up with the Black Team to spin a deceitful narrative, convincing Ozawa that Kang-in is dead. Ultimately, Kang-in intervenes to prevent Ju-yeon from erasing critical details under Ozawa's coercive tactics, while Ji-hoon cleverly maneuvers Ozawa into eliminating the list, thereby triggering a program that exposes all of Ozawa's clandestine operations and double agents.
In a dramatic conclusion, Ozawa meets his demise, and Director Yeom faces arrest for his involvement. Following this intense whirlwind, Ji-hoon makes his way back to the Seoul Central District Prosecutors' Office, ultimately succeeding in bringing the chairman of the Sangin Group to justice.
In a thrilling epilogue, Ji-hoon receives a message from Kang-in, inviting him to rejoin the Black Team members, who are now scattered around the globe, as they prepare to assemble in London for a new, mysterious mission that promises to be just as perilous as their previous encounters. The call to action resonates with Ji-hoon, reaffirming his commitment to a life entangled in adventure and high-stakes espionage.
