Episode 2 of "Trigger" kicks off with a haunting flashback to a younger Lee Do, who bears witness to the brutal murder of his entire family. Cho Hyun-sik, driven by compassion, guides the traumatized youth to the police station for a statement, carelessly leaving his service pistol atop a table as he hangs his coat. Lee Do's eyes, brimming with rage and sorrow, fall upon the gun, contemplating using it to end the taunting killer confined within a police cell.
Present-day, Lee Do and his team race to a boarding house where Jeong-tae's murderous rampage continues unabated. The first responders, two police officers, aim their weapons at Jeong-tae, but his relentless determination remains unshaken. Bullets fly, injuring one of the officers, prompting Lee Do to devise a daring plan to distract Jeong-tae while his colleagues rescue as many innocents as possible. In a climactic confrontation, Lee Do disables Jeong-tae by viciously slamming his head against the wall.
Detective Seo and the crime unit, reinforced by Chief Yoon and Captain Ju, arrive to secure the scene. Lee Do enters Jeong-tae's room, sitting on the bed only to find it strangely rigid. Curiosity piqued, he lifts the blankets to uncover a cache of firearms concealed beneath. The detectives confiscate the guns, prompting Chief Yoon to task Detective Seo with finding a military expert to analyze them.
When Seo enlists Lee Do's help, Captain Yoon casts a disdainful glance his way. However, Lee Do's skill is undeniable as he effortlessly assembles the three guns, astonishing the roomful of officers. He reveals that these firearms have seen action in overseas conflicts and notes that the bullets from a previous case are perfectly compatible, suggesting a chilling connection between the two incidents.
Elsewhere, Jung-man and his henchmen wait outside an establishment, poised to clean up the mess left by their employer, Seok-ho. After Seok-ho's men force the owner to sign over his business, Seok-ho bestows ownership upon Yong-gu and departs, leaving Jung-man to oversee the grim cleanup. Jung-man's crew packages bodies into sacks, their actions a grim testament to their ruthless employer's influence.
Meanwhile, at the hospital, Jeong-tae defiantly refuses to cooperate with Captain Ju, insisting that he will only speak to Lee Do. Under Lee Do's questioning, Jeong-tae reveals that the guns were delivered to him via courier whenever he needed them, hinting at a shadowy figure orchestrating the chaos from behind the scenes.
He asserts that a single firearm was all he required, yet the sender overstepped by providing him with more, igniting a rage within him. He uncovers the existence of additional armed individuals, but the police remain skeptical of Jeong-tae's claims, despite his steadfast insistence on the truth. Unbothered, Lee Do finds the entire scenario peculiar and continues his silent investigation.
Elsewhere, Gyu-jin and his companion Yeong-dung find themselves cornered by a group of bullies. Seong-jun, the leader of the gang, expresses his discontent over their failure to complete their assigned tasks. Though the students vow to improve, the bullies eventually relent and let them be. Meanwhile, other bystanders watch from afar, cowering and offering no assistance.
Concurrently, Won-seong, a convicted sex offender, attempts to procure groceries at a supermarket. The other shoppers cast disdainful glances and whisper behind his back, provoking his anger. Frustrated, he exits the store and retreats to his home, only to discover two parcels addressed to his alias awaiting him outside his door. Upon opening them, he finds two guns – a K1 and a K2 – which he expertly assembles.
Turning our attention to Jung-man and his henchmen, they find themselves in the midst of the desert, engaged in the gruesome task of burying bodies. Among them, Mr. Kim, miraculously still alive, tries to negotiate for his survival. He reveals to Jung-man that Seok-ho intends to betray him by giving the business they seized to Yong-gu instead. Jung-man's men are skeptical, believing Mr. Kim will say anything to save his skin, especially when he offers to arm them with hundreds of guns to confront Seok-ho. To verify the truth, Jung-man calls Seok-ho, who reassures him of the deal's validity. Unconvinced, Jung-man brutally strikes Mr. Kim with a shovel, sealing his fate.
The following day, Won-seong ventured up a mountain, armed with his firearms. He chose to hone his shooting skills beside a military training facility, cleverly concealing his gunfire amidst the echoing shots from the base. Meanwhile, Lee delved deeper into his investigation, scrutinizing customs records for any firearms that might have slipped through the cracks.
Jung-man dialed Seok-ho, eager for an update on the cleaning gig and a reminder about the business transfer they had discussed. However, Seok-ho dashed his hopes, revealing plans to bequeath the venture to Yong-gu instead. He advised Jung-man to remain patient, continue his hard work, and await his turn. Dejected, Jung-man dismissed his employees to enjoy a meal and a shower, while U-tae accompanied him on a quest to uncover the firearms mentioned by Mr. Kim.
Elsewhere, Gyu-jin received a text from Seong-jun, urgently requesting his mother's ID. Torn between complying and questioning the motive, Gyu-jin even sought counsel from his mother, who toiled away in a restaurant. Ultimately, he declined, realizing Seong-jun intended to use the ID to borrow money from a loan shark. This refusal incited the bullies, who ganged up on Gyu-jin for his defiance.
Jung-man and U-tae stumbled upon Mr. Kim's car, only to discover a gun and ammunition hidden in the trunk. U-tae cautioned against impulsive actions, urging Jung-man to think things through carefully. Yet, Jung-man, weary of Seok-ho's crumbs of favor, saw this as his long-awaited break. Clutching the weapon, he deemed it his ticket to a new destiny.
As night fell, Lee Do pursued the enigmatic figure who had orchestrated the gun shipment. He canvassed the boarding house, querying its inhabitants about mysterious parcels, to no avail. Just as despair threatened to set in, he encountered a gang of delinquents rummaging through stored delivery boxes nearby. After dispersing them, he received a call from Captain Ju, insisting Jeong-tae's tale of receiving a parcel was a fabrication. Captain Ju revealed that Jeong-tae hadn't received any parcels in the past three years. Lee Do nearly succumbed to defeat, but a box adorned with a recognizable sticker caught his eye, jogging his memory of a similar package outside Won-seong's residence.
Hastily, he alerted Detective Seo, asserting that Jeong-tae and Won-seong had indeed received packages. Detective Seo and his squad were already trailing Won-seong for violating his ankle monitor restrictions. They traced the signal but found that a benevolent father and son had offered Won-seong a ride, unwittingly left with his monitor and phone aboard.
In the climax of Trigger Episode 2, Lee Do stealthily infiltrated Won-seong's abode. Though Won-seong was nowhere to be found, he encountered Moon-baek, who claimed to be searching for a parcel too.
