Uncover the truth behind historical events that took place in Korean apartments! What secret does Woosang Apartment hold? Six residents are summoned to the apartment in 1998 and are led somewhere unknown by strange sounds. Their chemistry sparks laughter, while growing doubts and suspicions bring twists! The variety show masters embark on endless deductions. Can they unveil the apartment’s secret?

A strange van follows a girl at night. Is the quest to find a missing girl? Strange sounds are heard outside, and a dangerous chase unfolds. What's the story behind the shocking true event? JENNIE uses her deductive skills while Na-ra shows her sacrificial side and thief mindset. The residents use their skills to the fullest and spare no means! Can they uncover the apartment’s secret?

In 1999, a bazaar opens inside an apartment complex, complete with a host of delicious Korean food. Time to chow down. A scream is heard in the distance, and the residents hit the jackpot! Then the apartment suddenly changes, and they all become suspects! Who is the real culprit? Find who will ascend the judgment stand. Amidst the endless suspicions and twists, will they unveil the truth?

The residents are joined by their first guest, Yeonjun of TXT! They suddenly get dragged away blindfolded. Uncover the secret of the Maple Leaf Apartment set against a real-life 1970s incident. A bingo board appears and pits those who want to make the perfect bingo against those who want to cash in! Look forward to Yeonjun’s performance and the mental battle between the residents!

The fifth case takes place in 1991. Nostalgic snacks and catchphrases are summoned as the members chat about the good old days. An ambulance and a police car appear at the apartment. People start foaming at the mouth and collapsing, and the members quickly get infected! Is the culprit among them? After making some wrong guesses, not many chances remain. Don’t walk, run! The rowdy chase starts now!

The members visit a nearby university and enjoy the clubs, cafeteria, and even an exciting flash mob. Suddenly, the six new students are startled by a surprising disturbance! Animal noises fill the air as the teams compete for a hint. Which team will win? At a place that is suspicious as usual, a rescue mission unfolds with a surprising roar!

A high school beside the apartment welcomes six transfer students! Both the actual incident and the scale of the episode are on another level! A group of boys fight over a girl in front of the new students. As strange events occur throughout the high school in 2003, they must find the hidden evidence and unveil the truth! Will the six students be able to uncover the hidden secret of the school?