Channel A's 'Detectives' Trade Secrets' focused on two real cases: fraud disguised as marriage and a large-scale investment scam.

■ 5 Billion Won Investment Scam That Began in a Department Store VIP Lounge

In the 'Case Notebook' segment, the case was revealed of the only daughter of a chairman living in a major regional city who was scammed out of 5 billion won after investing it in a woman she met in a department store VIP lounge. Despite the coldness of those around her, the victim formed a close relationship with the woman, who approached her warmly. She was deceived into handing over the investment money by claims that the woman's husband ran a dessert boutique in Gangnam and a proposal guaranteeing shares equal to the investment for early investors.

However, contact was subsequently cut off, and the husband turned out to be a hired actor. More shockingly, it was revealed that the victim's husband and the woman she believed was her 'soulmate' had been lovers in the past. The husband reportedly planned to marry the chairman's daughter, receive a division of assets on fault-based grounds in a divorce, and then remarry his first love. The victim has filed a criminal complaint for fraud and is also pursuing an adultery lawsuit and a divorce suit worth 10 billion won.

■ Demand to Be Registered as CEO... Turned Out to Be a Ghost Company

In the 'Detectives 24 Hours' segment, a case was covered in which a 55-year-old man requested an investigation into the identity of his girlfriend, six years his senior. The woman worked unpaid for five months for the client's corn wholesale business, and the two promised to marry after just four months.

The girlfriend then took 70 million won under the pretext of investment. She subsequently asked for documents in the client's name, including his mobile phone, personal seal, and ID, requesting to be appointed CEO of a business she had acquired. The client was indeed registered as CEO of the business in January 2026, but soon a flood of mail arrived, including notices of unpaid corporate taxes and overdue payments on expensive imported rental cars. In the car's trunk, debt collection letters from a credit information company and even court documents were discovered.

The detective team and attorney Nam Sung-tae determined that the submitted documents were related to loans, and the business in question was confirmed to be a ghost company, registered only in address with no actual operations. It was also reported that the girlfriend, together with a prison acquaintance, had committed vehicle scams ranging from at least 30 billion won up to as much as 100 billion won.

■ "Can I just swear once?"... Cast Members' Outrage

During the broadcast, Defconn expressed his anger, saying, "Can I just swear once?" while Kim Poong and Yoo In-na could not hide their shock at the dismissive attitude toward the client. Lee Hyun-yi lightened the heavy mood with a video letter saying, "I married you because you're a salaried worker. I love you."

Meanwhile, 'Detectives' Trade Secrets' airs every Monday at 10 p.m.