Yadang: The Snitch 2025

[Lee Kang-soo] profits by providing drug intel to the prosecution, while his partner, ambitious prosecutor Goo Gwan-hee, gains career success from these arrests. Kang-soo was a young man who supported his mother while working as a designated driver. His life changes when he is tricked by a customer into consuming a drug-laced drink and unjustly jailed. Goo recognizes his sharp memory and recruits him to befriend the imprisoned head of a drug trafficking ring, and successfully gathers intelligence on the organization through him. Their partnership flourishes, and Kang-soo becomes a yadang (an informant or undercover operative), while Goo rises through the prosecutorial ranks.

Meanwhile, narcotics officer Oh Sang-jae arrests actress Um Soo-jin for drug use, only to find his investigation undermined by Kang-soo and Goo, who swoop in to seize major busts, including one involving a presidential candidate’s son, Cho Hoon. When Cho’s powerful allies offer Goo advancement, he betrays Kang-soo, crippling him in a staged overdose attack. At the same time, Goo frames Sang-jae and Soo-jin to erase evidence of the drug party and protect Cho. Kang-soo survives, barely escaping with his life, while Sang-jae spends months clearing his name. Eventually, Kang-soo, Sang-jae, and Soo-jin realize they share a common enemy and form a pact for revenge.

The trio targets different figures: Kang-soo aims for Goo, Sang-jae for dealer Yeom Tae-soo, and Soo-jin for Cho Hoon. At first, Kang-soo and Sang-jae successfully subdue Yeom Tae-soo and obtain incriminating evidence, while Soo-jin films a drug party hosted by Cho. However, Detective turns out to be a spy for Goo and tips off Cho. A car crash orchestrated by Cho’s men kills Soo-jin and Kang-soo’s close acquaintance Chang-rak, devastating Kang-soo. Though tempted to give up and leave Korea, Sang-jae convinces him to stay the course.

Goo, seeking to secure Cho’s father’s political future, orchestrates a scheme to fake drug-test results and protect Cho. However, Kang-soo anticipates Goo’s ploy. He secretly records incriminating conversations by swapping Goo’s lighter with a hidden recorder and live-streams them to the public during the presidential debate. Simultaneously, Goo’s hitmen sent to kill Kang-soo are murdered by rival gangs. Goo realizes too late that he has been completely outmaneuvered. Furious, he confronts Kang-soo but is easily defeated. Cho’s father withdraws from the election, Cho spirals into madness and jumped to his death, and Goo is arrested.