Nine Puzzles arrives as a South Korean thriller that stitches together two investigations separated by ten years. It opens in a rain-drenched schoolyard, where teenager Yun I-na (Kim Da-mi) stumbles on her uncle’s murder, only to lose all memory of how she got there.

A decade later, she’s become a criminal profiler haunted by that case, still clutching the first puzzle piece left by the killer. When a new child-murder mirrors her uncle’s demise—complete with another cryptic puzzle piece—I-na is forced to team up with Detective Kim Han-saem (Son Suk-ku), the very investigator who once branded her suspect.

The series unfolds over eleven hour-long episodes, released in two batches. Its atmosphere is steeped in shadow and tension, favoring patient scene-setting over rapid-fire action. While steeped in genre conventions of the ‘haunted cop’ thriller, it carries a distinctly measured pace, teasing out clues and character...