OBSESSED

Another troubled soul for neuropsychologist Dr. Peter Zak, this time not a patient but a colleague.

Someone is stalking Dr. Emily Ryan, a postdoctoral student Peter (Addiction, 2001, etc.) is mentoring at Boston’s Pearce Neuropsychiatric Institute. And it’s not just a romantic fantasy gone awry. Whoever’s following her is keying her car, letting the air out of her tires, and stealing her stuff. Peter wonders if the stalker isn’t Emily’s ex, gym teacher Kyle Ronan, who “majored in beer and sports”—until he realizes that Kyle thinks the stalker is him. As the threats against Emily mount, they seem to engulf other people at the University Medical Imaging Center, where her boss, Dr. Jim Shands, is using an ultrapowerful MRI to diagnose cases of Lewy body dementia in search of a therapy for patients who usually die within a year or two. The problem is that Shands’s patients seem to die even earlier, as Peter realizes when he persuades his lover, attorney Annie Squires, to bring in her uncle, retired Somerville cop Jack O’Neill, for an MRI and he contracts a nasty case of pneumonia. What’s the connection between Emily’s stalker and the dangers lurking within the MRI supermagnet’s core of liquid helium? Only a series of violent deaths will tell.

Peter’s fourth case is his most conventional, moving from genuinely disturbing hints about Emily and her stalker to well-worn medical-thriller territory and a finale out of James Bond.