As a young girl, Kang Gwon Ju was in an accident that temporarily caused her to lose her sight. Although her memories of that time are faint, she developed extra-sensitive hearing following the accident. As an adult, Gwon Ju became a police officer like her father. But when he is killed in the line of dutry, Gwon Ju blames herself for not being able to save him.  Taking a leave of absense from her duties, Gwon Ju goes to the U.S. to study voice profiling, hoping she can redeem herself through saving other victims.

When she returns, at her request, she is placed in charge of the newly formed  Golden Time team. Using voice and audible clues, Gwon Ju helps her detectives solve  time-sensitive violent crimes. But the traumas of her past will become increasingly hard to ignore as certain cases expose more of her lost memories.

Kang Gwon Ju is aloof and a rigid rule follower. She sees justice clearly in the form of black and white. But as each of her partners struggles with their own personal issues, Gwon Ju is forced to broaden her understanding of justice. Through all of it’s shifting cases and cast, Lee Ha Na really holds this drama together and I loved seeing Gwon Ju’s abrasive personality soften with each season.

Do Kang Woo grew up in Japan before moving to Korea. He has no clear memories of that time. But after a childhood friend is murdered and his family all die, Kang Woo is forced to leave Japan and start fresh. Psychological profiles from that time cite Kang Woo’s behavior as sociopathic. But as an adult in Korea, Kang Woo has left that life behind him.

Now he is a skilled police officer with a reputation for being able to analyze serial killers and their thoughts and patterns. But privately he is struggling to hold his own anti-social tendencies in check. Even the illegal medicine he is using seems to be less effective as time goes on.  So when a case brings him right back to the place where all his struggles started, he gets a chance to confront his own demons and find out the truth about what happened the day his friend was murdered.

Do Kang Woo keeps to himself, more to protect others than himself. He often needs to take extreme measures to keep himself from blacking out and hurting someone. But he has no idea that most of the traumatic memories he has are flawed versions of what really happened.  Lee Jin Wook plays these dark, conflicted roles well and I felt like he was perfect for this series.

Moo Jin Hyeok is Gwon Ju’s first partner on the Golden Time team. He is a devoted police officer. But when his wife is murdered, he becomes obsessed with the need to find her killer and see him punished. He and Gwon Ju bond over their own guilt for not saving their loved ones, and eventually learn that the same killer murdered them both.

Derek Jo is Gwon Ju’s partner in season 4. He actually works for the LA Police Department, but is in Korea for a joint investigation. When his sister, who came with Derek as a tourist, is killed, he decides to stay in Korea and help the Golden Time team find the person responsible.

Sim Dae Sik is close friends with Moo Jin Hyeok. They work together as police officers in season 1. But we find out that Dae Sik is actually spying on Jin Hyeok for the higher-ups, and his actions almost cost him his life. He quits the force and disappears, but in season 4, he runs into the team and comes back to help them solve a local crime.