Episode 3 of "Trigger" unfolds at the bustling docks, where boats bob gently against the shore, hauling mysterious boxes from the depths of the sea. Amidst this backdrop, two enigmatic gang leaders convene for a cloak-and-dagger exchange. Elsewhere in the narrative, the relentless pursuit of Won-seong by the police intensifies, while Lee Do confronts Moon-baek at Won-seong’s abode.
Moon-baek reveals a tale of intrigue, recounting how he received a mystifying box filled with bullets accompanied by a list of addresses and phone numbers. Driven by curiosity, he traced one of the addresses, which led him straight to Won-seong’s residence. Hesitant to venture inside, Moon-baek lurked around the perimeter until he spotted Won-seong departing. Seizing his chance, he slipped inside to investigate.
Meanwhile, Won-seong trudges through the streets, the fishing bag slung over his shoulder and still heavy with firearms. Lee Do, determined to track him down, calls Detective Seo, who confirms that no guns were found in the taxi. He promptly contacts the CCTV control room, requesting assistance in pinpointing Won-seong’s whereabouts.
At this crucial juncture, Moon-baek detects a flicker of movement outside the door. Switching off the light to bait the potential intruder, he suspects it could be Won-seong returning. Eager to aid Lee Do in his capture, Moon-baek dashes outside. However, his quarry proves to be U-tae, not Won-seong. As Lee Do receives a callback from the CCTV operator with details on Won-seong’s citations, he leaves U-tae trussed up on a post and summons Officer Jang to secure him.
With the chase reignited, Moon-baek employs his exceptional driving prowess to retrace Won-seong’s steps, guided by the CCTV operator’s instructions. They navigate through labyrinthine alleys and dark underpasses, converging on a bustling city center. Despite the operators’ best efforts, Won-seong seems to have vanished into the throng. Lee Do notices a street sign pointing towards their precinct, sparking a memory.
Recalling his last confrontation with Won-seong, Lee Do reflects on his rant about the police encroaching upon his life, suffocating him with their presence. Seizing upon this insight, Lee Do tasks the CCTV operator with confirming his suspicions. The operator reveals that Won-seong was last seen heading towards the very police station where Lee Do stands.
Lee Do urgently summons Captain Joo, instructing him to secure the police officers stationed at the precinct to safety. Finding all active-duty officers engaged elsewhere, only the administrative staff remains within the station's walls. With resolve, Captain Joo arms himself, swapping out his gun's blanks for live ammunition, and dashes out to confront Lee Do. Meanwhile, Lee Do secures Moon-baek to his vehicle with handcuffs and proceeds to join Captain Joo.
Inside, chaos reigns as Won-seong unleashes his deadly rampage upon the officers. His reign of terror begins in the supervisory office, where he tracks an ankle monitor's signal before executing his parole officer and two more officers at close range. His murderous spree continues unabated, targeting anyone who crosses his path within the precinct. Upon their arrival, Lee Do and Captain Joo realize that their standard-issue sidearms stand no chance against Won-seong's powerful K1 rifle. Lee Do swiftly devises a plan to divert Won-seong's attention while Captain Joo escorts the remaining officers to safety.
The strategy nearly succeeds, but an officer's misstep on shards of glass alerts Won-seong to their escape route. Abandoning his pursuit of Lee Do, Won-seong redirects his fury towards the fleeing officers. Though Captain Joo bravery takes a bullet for his comrades, Lee Do dashes outside to retrieve bullets from Moon-baek's vehicle. Freeing himself, Moon-baek trails Lee Do back inside, with a persistent reporter hot on their heels.
Inside, officers frantically attempt to stem Captain Joo's bleeding, while Lee Do, himself wounded, searches the evidence locker for weapons. Following a trail of blood, Won-seong zeros in on Captain Joo. Amidst Lee Do's struggle with his military trauma, vivid flashbacks assaulting his mind, Won-seong prepares to end Captain Joo's life. At the eleventh hour, a police officer draws a bead on Won-seong and fires, just as his finger tightens around the trigger.
As if on cue, Lee Do snaps out of his reverie, gun poised, and engages Won-seong. A bullet to the leg brings Won-seong crashing down, yet his frenzy escalates, bullets flying willy-nilly. Yet, Lee Do leaves him no room to retaliate, his resolve unwavering.
He employs a tactical maneuver, rendering it virtually impossible for Won-seong to take aim by strategically shooting out the lights and enclosing him within a confined space. Cornered, Lee Do demands Won-seong's surrender with authority. In a clever ruse, Won-seong feigns capitulation by relinquishing one of his firearms while inching his way toward an adjacent room where Captain Joo and the police officers are concealed.
Lee Do's mind drifts back to a haunting memory from his military days. It was then that he swore off using guns, unwilling to confront the harrowing dilemma of sacrificing one life to spare another. Recalled is the harrowing instance where he was compelled to eliminate a young boy who had trained his gun on the army officers. Despite his earnest pleas for the boy to lay down his weapon, the latter persisted, leaving Lee Do with no choice but to end the boy's life to save his comrades. In a harrowing parallel, Lee Do finds himself compelled once more to pull the trigger, this time taking down Won-seong to safeguard Captain Joo and the police officers. The entire harrowing sequence is unfolding before the lenses of vigilant reporters, their cameras capturing every tense moment.
