The January 5th tweet sent amateur sleuths back to the drawing board to re-examine previously abandoned leads in the hopes of solving the mysterious puzzle ... text on a black background.

When a new wave of serial killings begins—once again tied to mysterious puzzle pieces—she is drawn back into the case. As she investigates, Detective Han Saem, who still suspects her ...

As the serial murder case resurfaces, Yi Na’s confused facial expression while staring at the mysterious puzzle pieces sparks questions about who sent them and why, deepening the mystery.