Dr.  Jack Stapleton and Dr. Laurie Montgomery have reached a turning point in their relationship of 9 years-Laurie is hearing the ticking of her biological clock and Jack isn’t yet ready for a family. In addition, she finds out she carries the genetic marker for breast cancer after her mother is diagnosed with it and discovers she is pregnant. As if this weren’t enough to deal with,  the Office of the Chief Medical Examiner (OCME), for whom Laurie and Jack both work, starts receiving autopsy requests on healthy individuals, all from the local Americare Hospital. All the individuals were at the hospital for very minor procedures and all suffered heart failure and, as it turns out, share the common trait of genetic markers for chronic illnesses.  With their relationship on-the-rocks, Jack and Laurie are determined to get to the bottom of these mysterious deaths.  The stakes are raised when Laurie is rushed to the hospital for emergency surgery due to an ectopic pregnancy and unwittingly becomes a target for the as yet unknown forces responsible for the deaths.

Marker by Robin Cook is yet another top-notch medical thriller by one of the masters of the genre.  I will warn you now, if hospitals make you jittery, do not read this novel.  This novel was written about 6 years after the completion of the first stage of the Human Genome project. The ramifications of this accomplishment is that at some point in the future, individuals could have their blood tested and be told if they possess the genetic markers for any given health condition, such as diabetes or cancer. However, the flip side is that this information could be used by the health insurance companies to deny coverage.  As always, Cook demonstrates attention to detail and gives the reader a glimpse of what the future may hold. As with his previous novels, I believe he is right on target.