UNSOLVED

Ten cases.

Two years.

One killer who never left a trace.

Lee Felix is Seoul Station's golden officer-cold, precise, and terrifyingly perfect. At just twenty-five, he's already solved more cases than most officers do in a lifetime. Praised by his superiors, respected by his team, feared by criminals-Felix should be satisfied.

But he isn't.

Because one case still bleeds through the files.

A serial killer who has been executing criminals for four years-and vanishing every time.

When four elite officers from Busan are transferred to Seoul to assist, Felix's controlled world is shaken.

Especially by Hwang Hyunjin-loud where Felix is silent, reckless where Felix is disciplined, smiling where Felix never does.

Forced to work together, rivalry turns into tension.

Tension turns into something far more dangerous.

As bodies pile up and suspicion shifts from face to face, trust becomes fragile, alliances crack, and love blooms in the worst possible place-between two officers standing on opposite sides of a truth neither is ready to face.

Because in a city built on lies and sirens,
justice isn't always clean-and monsters don't always hide in the dark.

Some truths aren't uncovered.

They're protected.