Rogi hears about Frank and Alice who are stressed out because of prank calls, and vows to catch the culprit. He sets out as a self-appointed detective with Gani. The only lead is that the culprit has a deep male voice. With that clue, Rogi and Gani try to find the culprit. But Rogi once again makes preposterous deductions and reasonings. A few days later, Rogi and Gani find out where the prank calls were made thanks to Rookie, and they plan a stakeout.