Detective Hansaem suspects Ena after she fails to remember anything about her uncle's murder.

A puzzle piece arrives on the same day as a murder, and Hansaem suspects it’s no coincidence.

Ena and Hansaem warily work together to solve the case.

A prime suspect emerges, but things aren't what they seem.

Another puzzle piece arrives, and a new murder case unfolds.

The meaning behind the drawings on the puzzle pieces is uncovered.

Hansaem makes a shocking discovery and becomes unsure of whom to trust.

As the investigation escalates, new suspects begin to emerge.

An unexpected suspect is arrested, shocking everyone involved.

The final puzzle piece arrives will the team be able to catch the killer in time?