“Everybody has a powerful protector, a silent saviour, a dauntless defender, someone who constantly makes selfless sacrifices for the other party without seeking personal desires. However, these sacrifices must remain a carefully guarded secret, sometimes, for one’s own safety, but always, always for the other party’s own good. Hence, many times, we are blissfully ignorant of who our guardian angel is, and we may even mistake them as our enemy. However, the unsung hero knows, in his or her own heart, that they have saved the other person, and that is enough for them. I have found my dark knight. What about you?”

Years ago, the police force was a corrupted force that would stoop to nothing to achieve its aims, and was willing to compromise society’s ethics, trying to do what they thought was right. However, they made sure to keep all of these dirty secrets well under wraps, never allowing their weakest spot to be exposed to the public. Due to their methods, they enjoyed large success in their work and attained public recognition. However, a fire cannot be contained by paper as cracks were slowly appearing beneath the surface, and more and more people were displeased with the police.

In year 2012, Officer Tiffany has attained an impressive track record of hunting down criminals with a vengeance over her five years of police work, and has never allowed a criminal to slip away once she was in charge of a case. As recognition for her efforts, she has been promoted to be the youngest superintendent ever in the history of Seoul’s police force. Tiffany was placed in charge of a small team consisting of herself, Yoona and Seohyun. However, such a young success story in the police force certainly attracts much attention, both from the light and the dark side.

On the other hand, Taeyeon has long been working with her two trusted partners, Yuri and Jessica, and has implicit trust in the two of them. With their aid, she was able to complete her missions with relative ease, which would have been a practical impossibility otherwise.

Taeyeon, after careful investigation of Tiffany’s background, decides to initiate contact with her to bring her into a partnership. However, she is afraid to tell Tiffany of the truth of her own background, fearing for her own safety if her identity was compromised. Tiffany, who is kept in the dark, is not knowledgeable of this fact and the lack of transparency between the two eventually leads to some problems in their relationship.

As problems within the police force begin to escalate, someone who has a grudge with the police force in the past has now returned and is aiming to destroy everything the police stand for with a vengeance, and Taeyeon and Tiffany must unite together to fight against this fearsome force against all odds. Through this, each of them finds their dark knight, but what sacrifices will already have been made?

Taeyeon

After living through the shock of losing both her parents and her only sister at a young age of 10, Taeyeon sees little purpose in her own life, realising that she has lost everybody who had once cared for her, and hence, she decides to live for only one purpose: to protect. Taeyeon then underwent a series of intense training, hoping to never have such a disaster unfold before her eyes ever again. However, her will to protect others oftentimes causes her to put herself in the way of danger just so that others can remain safe and sound, much to her friends’ distress.

Tiffany

Tiffany has always believed that she was the cause of the death of someone important to her, and has always blamed herself ever since. Because of the nature of that person’s death, Tiffany has decided to dedicate herself to fighting crime, and does so with a vengeance, seemingly trying to convince herself of one thing: That she is slowly repaying for her sins, and that eventually, perhaps her guilt can be lifted once and for all. She often works overtime analysing cases, but never finds it a chore as this is the path she has chosen for herself.

Jessica

Jessica works as one of the highest skilled doctors in Seoul’s largest general hospital, and occasionally works with Yuri to try to advance medical research. Jessica went to the same university as Yuri, but majored in medical sciences whilst Yuri majored in physics. Jessica treats Taeyeon as her older sister and hence cares a lot about her, but never mentions it outright as she prefers to keep her ‘ice princess’ impression.

Yuri

Yuri is working in the police R&D department, but finds the job a chore as the police limit her research, and she is unable to find fulfilment in her job. After meeting Taeyeon, she is finally able to put her creativity and knowledge to practical usage and serves as Taeyeon’s private armourer. Unfortunately, being in the governmental institute for so long, she has gained the bad habit of cutting costs as far as possible, sometimes even reducing the quality of her innovations, much to Taeyeon’s annoyance. 

Yoona

Yoona went to the same high school as Seohyun. When their graduation days came, Seohyun suddenly told Yoona of her desire to join the police force.  Yoona, wanting very much to stay beside Seohyun, decided to go against her parents’ wishes and went to the same police academy as Seohyun. However, knowing that Seohyun prioritises mutual respect between family members, she fears that Seohyun would be unsupportive of her decision, and has never confessed to Seohyun of the sacrifice that she had to make.

Seohyun

Seohyun lost all her memories when she was merely 8 years old, and when she woke up in a hospital, she found out that her family was robbed and that she was the only surviving member left in her family. After being sent to an orphanage and growing in an unfamiliar environment, she naturally adopted a constant polite and respectful front, and this has become her nature. She enjoys the company of Yoona, who has gone to the same high school and also the police academy with her.

Sunny

Worked as a detective in Seoul’s police department for 3 years, before being transferred over as a new member of Tiffany’s team. Very little is known about her background.