Stranger (Secret Forest)

Hwang Shi Mok, a literally emotionless prosecutor, investigates a murder of an acquaintance. He meets Lieutenant Han Yeo Jin while on the case.

When Kang Jin Seop commits suicide, Shi Mok and Yeo Jin both look to reinvestigate. Unfortunately, the two aren't always on the same page.

Shi Mok decides to reveal his involvement in the Huam-dong case to the public, promising to find the real culprit within two months.

Shi Mok begins looking into a new, unexpected suspect, but he must tread lightly. Yeo Jin is ordered to report on any information Shi Mok has gathered.

News of another murder spreads quickly, but not all is as it seems. Shi Mok's personal investigating ends up getting him into trouble.

A pop song aids Shi Mok and Yeo Jin in their investigation of Ga Young's attacker. Park Kyung Wan is discharged early from the army.

Yeo Jin secretly follows Prosecutor Seo, hoping to learn more about his association with Ga Young, but Prosecutor Seo soon sets his sights somewhere else.

Shi Mok and Yeo Jin catch Prosecutor Seo red-handed, but that doesn't mean the case is solved. Eun Soo takes matters into her own hands.

Shi Mok is chosen to lead the internal investigation at Seoul Western, and he assembles his team immediately.

Yeo Jin tries to keep the now-conscious Ga Young safe. The truth about Eun Soo's father comes out.

Yeo Jin plots to prove Chief Kim's guilt to the rest of her station. Shi Mok pushes Ga Young to remember and point out the men she was involved with.

Shi Mok meets with the CEO of The Sungmoon Daily. The special unit faces potential disbandment.

A home invader sends a wordless message to Shi Mok. The special unit is officially dissolved without their agreement.

Shi Mok's non-reaction to the latest murder puzzles those around him, but it begins to affect him unexpectedly. The police try to determine if they're dealing with a serial killer.

Shi Mok learns the true culprit's motives for murder, but believes there is more to the story. Yeo Jin feels an overwhelming sense of guilt.

In the dramatic final episode, Shi Mok faces off with Lee Chang Joon, but he must unweave the tangled web of corruption surrounding the senior secretary as well.