Channel A's 'Detectives' Trade Secret' tracks the truth behind the disappearance of a college student who has been missing for two weeks.

The client for this episode is the missing student's father. He lost his wife in an accident seven years ago and has since lived relying on his only daughter. His family was so close with his wife's best friend's family that they were like family to each other, and the two daughters entered the same university and the same department and were close friends.

However, one night, a call from his daughter contained only a scream before the line went dead. Afterwards, she could not be reached for more than two weeks. Police contacted the daughter, but she said she had left home of her own will and did not want to reveal her location. The father, insisting his daughter had no reason to leave home on her own, grew suspicious of the case.

To trace the daughter's whereabouts, the detective team met her closest friend and the friend's mother. It was confirmed that their last meeting was a trip the two families took together three days before the disappearance.

As the investigation stalled, the owner of a bar the daughter frequented offered new testimony. According to the owner, on the day of the disappearance, the daughter came to the bar alone, and her best friend soon joined her. The two ended up in a heated physical fight after an argument. The owner added that the cause of the quarrel 'seemed to be over a man.' The bar's CCTV footage captured the two fighting. The detective team focused on the fact that the best friend had hidden that she had met the daughter on the day of the disappearance.

At what was revealed afterwards, the cast members expressed shock and anger. Yoo In-na said, 'How could something like this happen…' and Defconn said, 'He gave up on being human.' The details of the case will be revealed on the broadcast.

Meanwhile, popular creator Tongdak Cheonsa will join this episode as a one-day detective. Tongdak Cheonsa shared her experience setting up a blind date between an employee of Chimchakman's company and an employee of a publishing house run by actor Park Jung-min. She also drew laughter by saying, 'The manager of a very famous celebrity once contacted me saying, "I've been broken up with."' Defconn nicknamed her 'the matchmaker grandmother of YouTube.'

Channel A's 'Detectives' Trade Secret' airs on November 9 at 10 p.m.