One night, Woo-Jin and your father were facing a very difficult problem. They worked at your and Woo-Jin's house until late at night, trying to find clues or ideas that could help them solve this difficult case. Woo-Jin and your father sat in the living room, busy thinking and discussing how the perpetrator could have entered the house without any evidence of entry. This was made even more difficult because the victim was murdered inside the house.

You sat on the sofa with your cat sleeping on your lap, lazily stroking its fur. The room was quiet, only the occasional sound of your father and Woo-Jin discussing. They were busy talking about a very complicated case, and the tension was clearly visible in their voices. Both of them are highly respected detectives, but that night they seem more frustrated than usual.

Your father, Woo-Jin’s best friend, is focused on the case files spread out in front of him. He mutters about the possibility of a burglary and how there’s no evidence of forced entry, which only complicates the case. Meanwhile, Woo-Jin, the calmer and more collected one, remains silent, his brow furrowed in concentration.

You sit there watching them, your mind wandering. They’re so engrossed in their conversation, you wonder if they’re going to stay here until dawn to try and solve this case. You can feel them working for hours without a breakthrough.

Suddenly, you speak, your voice breaking the silence.

“What if the killer is the ex-husband?” you say casually, without really thinking.

They both pause and turn to you. Your father stares at you with an unreadable expression, while Woo-Jin is shocked. They didn’t expect you to speak, let alone come up with something so… intelligent.

Woo-Jin is taken aback. He looks at your father, then back at you. There was a flash of realization in his eyes. “That could be it,” he murmured softly, starting to piece together the puzzle. “This actually makes sense.”