Walker wrote Search for the Nile, book twelve in the Time Machine series, a game book series of twenty five books written by various authors from 1983 through 1989. He has written eight non-serial novels as Walker, Hale and Kingsbury. He has written ywenty one additional novels in four series; the Grant series, the Lucas Stonecoat series, the Jessica Coran series and the Abraham Stroud series written as Geoffrey Caine.

The Jessica Coran series, also known as the Instinct series presently has a total of eleven novels written between 1992 and 2004; Extreme Instinct is number six in the series, written in 1998.

Jessica Coran, an FBI forensic pathologist is faced once again by a vicious serial killer, Feydor Dorphmann. Coran, in Las Vegas on a Medical Examiner’s Convention is dragged into the realm of the psychopathic killer who drugs his victims and calls Dr. Coran so that she can hear them scream as he burns them alive.

The murders are based on the fourteenth century novel Dante’s Inferno and the nine rungs of Hell. In the midst of the chase to trap the madman before he kills again, Coran learns that even those whom she knows and trusts cannot be trusted, for no one, not even FBI employees are safe from the grip of a mobster.

In the end, Jessica faces Dorphman alone, a final showdown occurs at Yellowstone National Park.

On a scale of one to ten, I give this tale a seven for being interesting. I give the tale a five on the scale for reading well; while the reader does not miss any important information from the series, the book is packed with technical information making it a slow read.