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?

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!