The Last Known Victim continues the lives of the Malone family following hurricane Katrina and shows how they have been affected by this tragedy (the first in the Malone family series is Bone Cold).

Captain Patti O'Shay patrols the deserted streets of New Orleans. Katrina had hit and all the "Doomsday" predictions had come true. There was a gigantic bowl of water that was once known as New Orleans. So many were missing. So many were dead. It was during this time post-Katrina that Patti's husband, also with the NOPD, was found murdered. It was believed he had been shot to death by looters, but with no manpower and no resources there was never an investigation into his untimely death.

A gruesome discovery is made at one of the refrigerator "grave yards". A half dozen human hands are found in one of the refrigerators; all belonging to women and all the right hand. It wasn't enough the city had Katrina's devastation and rebuilding process to face, now they had a serial killer to catch as well.

Two years after Katrina, a body is found missing the right hand and Captain Sammy O'Shay's badge is found with the body. This sheds new light on the murder of Sammy O'Shay and gives Patti the opportunity to search for the answers she has longed for since that awful day hurricane Katrina came barreling in and forever changed her world. She teams up with a twenty-two year old stripper everyone else on the NOPD has branded a liar. But Patti just has a gut feeling Yvette is the only one who can lead her to the answers she seeks.