When Justice Fails tells the story of Tom Chaney and Rod Lambeau, two Homicide detectives in the NYPD who are recently partnered. Both detectives are somewhat outsiders in their own ways - Tom, still supporting his crooked ex-partner who was his only true friend on the force, and Rod, who is openly gay.
Their first cases involve the separate murders of Dean Harvey and William Boxler, two men who were charged but not convicted of violent sexual assault. Both victims were poisoned and had their hair haphazardly shorn in what appears to be a ritualistic act.
One common bond between the victims is that they were both tried by D.A. Katy Wesson, who is deaf and relies on her friend Josh Kane as her interpreter and protector. Tom and Rod suspect Katy due to her connection to the victims and her success as a D.A.
Despite initially viewing Katy as a suspect, Tom becomes romantically involved with her, causing tension with Rod and Josh. Rod becomes more convinced of Katy's guilt as evidence mounts, while Josh tries to explain it away. Katy is aware that she is still under investigation by Tom and Rod.