Haunted by tons of unresolved murder cases that keep him awake at night, brilliant Busan detective Hae-Jun stumbles upon what seems like an accident. And suspecting foul play, the inquisitive officer follows a faint trail of clues, trying to shed light on the mysterious death of avid climber Ki Do-soo. Now, the deceased's cryptic wife, Seo-rae, is under suspicion. However, something doesn't add up. Has the dark-eyed widow been toying with Hae-Jun from day one? When forbidden feelings cloud judgement, how far is Hae-Jun willing to go in the name of truth?