Original: 불야성
A coldhearted heiress, a man from her past and an ambitious new hire in her company all become entangled on a battleground for money and power.
Barefoot and drenched in rain, Se-jin stops Yi-kyung's car. Flashback to a week earlier, the two women meet for the first time at a charity auction.
Waiting for Se-jin are two Chinese-speaking men, but no picture is to be found. Meanwhile, the general meeting begins without Yi-kyung present.
Bored with her first assignment, Se-jin gladly accompanies Tak on his errand. Despite being given strict rules, Se-jin gets a little too curious.
The fateful encounter between Park Gun-woo and Yi-kyung occurs 12 years ago in Japan with a misunderstanding involving a scammer and a broken guitar.
Yi-kyung and Gun-woo finally come face to face. Unlike Gun-woo, who is saddened by their bitter reunion, Yi-kyung maintains her emotionless façade.
Jang Tae-joon, hoping to pull both Yi-kyung and Gun-woo to his side, suggests the two work together. However, neither is willing to make compromises.
For Se-jin's next assignment, Yi-kyung asks her to steal a man's heart. For Gun-woo, winning Tae-joon's support may mean putting his father second.
While Yi-kyung visits Park Moo-il to acquire hints about Jang Tae-joon's weaknesses, Gun-woo meets with Tae-joon to declare where his loyalties lie.
Yi-kyung manages to get Park Moo-sam and herself invited to Jang Tae-joon's office. The news of their private meeting reaches Gun-woo's ears.
After hearing the real reason for Yi-kyung's visit to the hospital, Se-jin becomes conflicted about helping her and comes to a difficult decision.
Gun-woo's plan to acquire joint management rights will come at a big price. Meanwhile, Moo-sam and Yi-kyung prepare to launch a counterattack.
Yi-kyung misses an important meeting due to a miscommunication from Moo-sam. She begins to sense that there are forces working behind her back.
Dissatisfied with Jang Tae-joon's move regarding Park Moo-il, Yi-kyung warns him to follow her plans. But Tae-joon orders her to know her place.
As a last resort, Yi-kyung uses her father's notebook against Jang Tae-joon. Meanwhile, Se-jin and Gun-woo continue their probe into Collin Company.
Yi-kyung disregards Jang Tae-joon's pick among the presidential candidates. Meanwhile, Gun-woo returns to his old office ready to protect his company.
After hearing Yi-kyung's plans for him, Tak packs up and leaves. Yi-kyung presents Kang Jae-hyun with a shocking offer to help him in the election.
Gun-woo offers a deal to the prosecutor who is investigating him for data theft. Se-jin meets with Son Eu-sung, not realizing Tak is spying on her.
Jang Tae-joon offers to help keep Kang Jae-hyun's company from being sold. While at the hospital, Se-jin learns how Tak began working for Yi-kyung.
Jang Tae-joon orders his secretary to search for Yi-kyung's weaknesses. Predicting this, Yi-kyung prepares to end the battle once and for all.
Despite his dad's objection, Gun-woo persists in his feud against Yi-kyung. By hiring hackers, he plans to break into Gallery S's computer system.
