A bound corpse emerges following a serial arson. The first responders to unite in the investigation.

Two fires break out in different locations. The first responders find themselves in a crisis.

The first responders and the NFS cooperate to uncover clues to the serial arsonist.

When a murder occurs at Myeong-pil's villa, Ho-gae leaves his post and joins the case. Kang Do-ha joins the National Forensic Service.

Do-ha concludes that the death at the villa was an accident, but Ho-gae continues his investigation. Do-ha uncovers the dark side of the neighbours.

An unidentified body is found after a brawl at a junkyard. A crisis arises during the autopsy.

Criminals plan to endanger the NFS building. Can the team safeguard the place?

The police and fire department respond to an urgent call about a horrifying incident regarding organ extractions.

Ho-gae delves into the investigation of Ma Joong-do's murder and reopens a past murder case and prison escape.

Ho-gae vanishes after a caravan explosion. Amidst the chaos, a showdown is drawing near.

Supported by the NFS, the first responders confront the sinister mastermind in a decisive showdown.