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

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

As the investigation escalates, new suspects begin to emerge.

Ena and Hansaem warily work together to solve the case.

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

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

A stunning truth behind the serial murders is revealed.

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

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

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

An unexpected suspect is arrested, shocking everyone involved.