A Shop for Killers Episode 4 plunges Ji-an directly into the hidden subterranean heart of Murthehelp and exposes a devastating betrayal that shatters her trust. As Min-hye stays behind in the upper house to engage a wave of incoming assassins in a bloody, close-quarters gun battle, Ji-an and Bae Jeong-min descend via a freight lift into a massive, temperature-controlled subterranean bunker. The bunker houses an astonishing weapons depot—rows of assault rifles, body armor, military supplies, and encrypted mainframe servers that monitor the global criminal underworld. While exploring the terminal, Ji-an discovers the rigid color-coded classification system that governs Murthehelp: Red Code for contract killers, Purple Code for espionage agents and data brokers, Yellow Code for post-operation sanitizers, and Green Code—reserved exclusively for Jin-man and his direct family members, granting them absolute immunity and prohibiting any Murthehelp client from ever harming them under penalty of extermination. The tension spikes when they encounter a reclusive, masked figure known as Brother, who has lived hidden in the bunker maintaining Jin-man's system architecture. Recognizing Jeong-min immediately, Brother panics and desperately passes Ji-an a pair of handcuffs, begging her to restrain Jeong-min before it's too late. Misreading Brother's erratic behavior and trusting her polite childhood friend, Ji-an makes a critical mistake: she defends Jeong-min and hits Brother over the head, knocking him unconscious. In a shocking and chilling turn of events, Jeong-min's meek demeanor vanishes. Smiling coldly, he reveals that he was never an innocent IT bystander—he was planted by Babylon to infiltrate Jin-man's safe house. He orchestrated the wiretapping that breached Jin-man's security and played an active, treacherous role in Jin-man's demise. Before Ji-an can react to the revelation, Jeong-min injects her with a paralytic drug, leaving her helpless on the cold floor as Babylon's hitmen prepare to breach the inner sanctum. Episode 4 serves as a gripping narrative turning point that upends everything Ji-an thought she knew. With the shocking reveal of Jeong-min's true allegiance, Brother incapacitated, and Ji-an immobilized deep underground, the episode ends on an electrifying cliffhanger that raises the stakes to an absolute fever pitch.