Dr. Dean Graves, M.E. is asked to help the Atlanta Health Department investigate a respiratory illness that's infecting-and killing-mostly young, healthy individuals. The victims of the deadly disease seem to be random, with no traceable source for the exposure.

As the illness with a 100% mortality rate spreads across Georgia, including Augusta where Dr. Graves lives and works, he starts to question whether this could be an act of bioterrorism. He and Kat, his assistant and the woman he loves, work to find a source, a cure, and a possible killer whose IQ may rival that of even Dr. Graves, himself.

But Dr. Graves' usually unwavering competence and mental capabilities are hindered by flashbacks, nightmares, and sleepless nights as he battles the PTSD brought on by his chilling interaction with Carter Ridge, the serial killer that kidnapped, tortured, and nearly killed him only a few months ago.

Too stubborn to admit he needs help or accept it when it's offered to him, he continues to spiral until Kat figures out a way to help him-therapy in the form of a chocolate lab that reminds Dr. Graves of his childhood pet.

Time is running out as more and more people fall victim to the mystery illness. Dr. Graves must find the answers while also keeping up with his other duties as Chief Medical Examiner-including the bizarre death cases that always seem to land in his morgue.