The clock struck midnight as thunder rumbled across the city. Detective Sarah Chen stared at the body sprawled before her. Blood pooled beneath the victim, spreading across marble floor tiles. Rain pattered against tall windows, distorting the crime scene's reflection. The victim's hand still clutched an emerald necklace, now broken. Lieutenant Peters knelt beside her, examining the fatal neck wound. Something about this murder scene felt different from the others. This was the third victim this month with similar wounds. The killer was sending them a message, hidden in plain. Sarah noticed a small paper folded inside the victim's pocket.