Genres: Thriller, Mystery, Sci-Fi

Fifteen years ago, a young girl was abducted on her way home from school, a crime witnessed by elementary school student Park Hae Yeong. Days later, the girl was found dead, but the police failed to catch the culprit, leaving the case unsolved and shaking Hae Yeong’s faith in the justice system.

Fast forward to the present: Hae Yeong has become a police officer and a skilled criminal profiler, driven by a desire to uncover the truth behind cold cases. One day, he stumbles upon a mysterious walkie-talkie—one that lets him communicate with Detective Lee Jae Han, a relentless cop working in the past.

Together with Detective Cha Soo Hyun, a tough officer who still carries the emotional scars of Jae Han’s disappearance years earlier, the trio embarks on a high-stakes mission that transcends time. As they connect across two timelines, they race to solve unsolved crimes, rewriting history and challenging fate.

With every message through the walkie-talkie, their actions ripple through the fabric of time, forcing them to grapple with ethical dilemmas and unforeseen consequences. But as the truth inches closer, so does danger—because some secrets were meant to stay buried. Will they manage to change the past without destroying their future?

Signal is a thrilling blend of mystery, suspense, and emotional depth, exploring the power of second chances and the thin line between justice and revenge. Buckle up for a heart-pounding journey that will keep you on the edge of your seat until the very last transmission.

Tags: Different Timelines, Butterfly Effect, Murder, Hwaseong Serial Murders, Suspense, Investigation, Death, Corruption, Time Altering, Smart Female Lead