A serial killer goes after those responsible for the wrongful imprisonment of a loved one.

A serial killer goes after those responsible for the wrongful imprisonment of a loved one.

When a prison riot erupts into violence, Red ends up face to face with the ring leader, a man who once held him hostage and nearly drove him mad; injured prisoners are moved to a crumbling, overstretched hospital.

The killer is still on the loose and Red's investigation is in crisis; the London hospital is no longer a place of safety, it has become a graveyard of pain; the killer seems to be taunting Red.

Although Joseph has now worked out the killer's message, Mel gets involved with the main suspect.