About Stranger (Secret Forest)
Stranger, known in Korean as Bimilui Sup and also released internationally as Secret Forest, is a tvN legal-crime thriller that first aired in 2017. The story follows Hwang Si-mok, a prosecutor who underwent brain surgery as a child to relieve a painful hyper-sensitivity to sound. The operation left him largely unable to feel ordinary emotion, which makes him a coldly logical investigator but an isolated and often misunderstood colleague. When a murder exposes a network of collusion between prosecutors, police, and a powerful conglomerate, Si-mok is drawn into a case that reaches deep inside his own office.
His investigation pairs him with Han Yeo-jin, a warm and instinctive police lieutenant whose empathy and persistence complement his detachment. Together they work to identify a corrupt sponsor arrangement and the people protecting it, even as the trail points toward respected superiors such as senior prosecutor Lee Chang-jun. The first season is structured as a tightly plotted whodunit in which the question of who can be trusted is as important as who committed the crime.
The 2020 second season reunites Si-mok and Yeo-jin amid a renewed conflict over the long-debated question of investigative authority between the prosecution and the police. Built around a new disappearance and a fresh web of institutional pressure, the season widens the show's focus from a single conspiracy to the structural incentives that allow corruption to persist. Created and written by Lee Soo-yeon, Stranger is frequently cited by critics as one of the best-written Korean dramas of its era for its restraint, moral complexity, and refusal of easy resolutions.