A serial killer terrorizes Northern Virginia, his ability to come and go baffling those pursuing him with zero success.

He disables the victims' WIFI, attacking them in bed, the cause of death exsanguination due to sharp force injuries.

This has been going on for six months when Dr. Kay Scarpetta is awakened by her phone in the early morning hours of June 12, her birthday. She's informed that the Phantom Slasher has struck again, only this time there are two victims, and one of them has survived, the scene Mercy Island and its notorious old psychiatric hospital. This is a modern ghost story, a ghastly apparition seen around the time the Slasher strikes in each case. The same figure in black is spotted levitating through the fog, and the technical explanation is one that's of keen interest to the CIA, even the White House.

It's up to Scarpetta to stop the Phantom Slasher before they strike again and vanish, leaving another trail of blood in their wake.